Hybrid function projective synchronization of chaotic systems with uncertain time-varying parameters via Fourier series expansion

In this paper, the hybrid function projective synchronization (HFPS) of different chaotic systems with uncertain periodically time-varying parameters is carried out by Fourier series expansion and adaptive bounding technique. Fourier series expansion is used to deal with uncertain periodically time-varying parameters. Adaptive bounding technique is used to compensate the bound of truncation errors. Using the Lyapunov stability theory, an adaptive control law and six parameter updating laws are constructed to make the states of two different chaotic systems asymptotically synchronized. The control strategy does not need to know the parameters thoroughly if the time-varying parameters are periodical functions. Finally, in order to verify the effectiveness of the proposed scheme, the HFPS between Lorenz system and Chen system is completed successfully by using this scheme.     

A new algorithm to compute the discrete inverse radon transform

The aim of this paper is to compute the discrete inverse Radon transform over ⁿ . The Radon transform is a function with domainS ^n–1×. It is shown that under different measure this function can be defined with domain ⁿ . In this case one can compute the discrete inverse Radon transform in the Cartesian coordinate system without interpolating from polar to Cartesian coordinates or using the backprojection operator.     

一种新的红外图像快速分割方法研究

研究红外图像目标分割快速优化问题。在高分辨率红外图像的分割中,红外图像存在数据量大、目标的边缘模糊和噪声较大等导致分辨率低和实时性差。为了快速准确分割,提出基于低尺度分割阈值预测的快速红外图像分割方法(LFIRS)。首先建立尺度阶数计算模型以确定保留原始红外图像目标基本信息所需的最小尺度,在分析多尺度过程对具有目标/背景强相关特性的红外图像进行分割阈值,建立多尺度红外图像分割阈值的相关模型(CLM),结合经典二维阈值法得到的最低两个尺度的阈值CLM模型参数,可以通过CLM模型与最小尺度的快速获取原始尺度的分割阈值,实现红外图像的快速分割。实验结果表明,改进方法提高了图像分辨和分割速度,且改善了分割效果。     

自适应Fourier分解思想在再生核W2 1 [a,b]空间的应用

在再生核$W_2^1[a, b]$空间中研究自适应正交贪婪分解算法, 利用能量下降最快的原理自适应性地构造出最佳$n$项逼近函数, 并从理论上证明其收敛性成立。最后, 实验验证了在$W_2^1[a, b]$再生核空间中, 利用正交贪婪原理构造的$n$项数值原函数比用等分结点构造出的最佳$n$项数值原函数收敛效果更优。     

基于群延时信息的超声信号处理方法

充分利用超声信号的群延时信息，结合短时傅里叶变换，给出了群延时对频率导数在时一频域中的分布，以此来反映时一频域中局部信噪比的强弱。在此基础上，进一步利用超声信号的群延时信息，极大地增强了缺陷信号。     

Thermal degradation behaviors of polypropylene with novel silicon‐containing intumescent flame retardant

The N‐[3‐(dimethoxy‐methyl‐silanyl)‐propyl]‐N′‐ (9‐methyl‐3,9‐dioxo‐2,4,8,10‐tetraoxa‐3,9‐diphospha‐spiro[5.5]undec‐3‐yl)‐ethane‐1,2‐diamine/dimethoxy dimethyl silane copolymer (PSiN II), which simultaneously contains silicon, phosphorus, and nitrogen, is synthesized and incorporated into polypropylene (PP). The flame retardancy is evaluated by the limiting oxygen index value, which is enhanced to 29.5 from 17.4 with 20% total loading of PSiN II. The thermal degradation behavior of PP/PSiN II is investigated by thermogravimetric analysis under N₂ and air. The PP/PSiN II sample degrades at 400°C for different amounts of time, and the process of degradation is studied by Fourier transform IR. The morphology of the char formed at 400°C for 10 min is investigated by scanning electron microscopy. The swollen inner structure, close, and smooth outer surface provide a much better barrier for the transfer of heat and mass during fire and good flame retardancy. The thermal stability of PP is improved by incorporation of PSiN II. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 2487–2492, 2005     

B 炸药中绝热剪切带形成机理的细观研究

通过对快速加载后Ｃｏｍｐ．药柱剖面的扫描电镜和光学显微镜观察分析，对Ｃｏｍｐ．Ｂ炸药在快速加载下剪切带形成机理的微观机制有了初步的认识。文中采用形变试样的剖面观察分析方法，针对固体药柱这种比较软的材料，如何进行磨样、抛光、浸蚀，作了一些尝试和探索，总结出一套有效的实施办法。对不同加载速率条件下受压缩的药柱中细观组织进行了观察、分析、比较，首次给出国产Ｃｏｍｐ．Ｂ炸药装药的原始细观组织形貌，以及快速加载后药柱中细观组织形貌。经过分析，得到冲击载荷下炸药装药中绝热剪切带形成、发展的定性认识，为分析Ｃｏｍｐ．Ｂ炸药装药受冲击载荷时热点形成机理提供了一些有益的实验依据。     

傅立叶变换红外光谱法在橡胶分析中的应用与进展

简介了用橡胶分析的傅立叶变换红外光谱透射法，漫反射ＦＴＩＲ法，衰全反射ＦＴＩＲ法，ＦＴＩＲ－光声光谱法，ＦＴＩＲ仪与各种仪器的联用，以及计算机技术在ＦＴＩＲ分析中的应用与进展。     

Fast finite difference Poisson solvers on heterogeneous architectures

In this paper we propose and evaluate a set of new strategies for the solution of three dimensional separable elliptic problems on CPU–GPU platforms. The numerical solution of the system of linear equations arising when discretizing those operators often represents the most time consuming part of larger simulation codes tackling a variety of physical situations. Incompressible fluid flows, electromagnetic problems, heat transfer and solid mechanic simulations are just a few examples of application areas that require efficient solution strategies for this class of problems. GPU computing has emerged as an attractive alternative to conventional CPUs for many scientific applications. High speedups over CPU implementations have been reported and this trend is expected to continue in the future with improved programming support and tighter CPU–GPU integration. These speedups by no means imply that CPU performance is no longer critical. The conventional CPU-control–GPU-compute pattern used in many applications wastes much of CPU’s computational power. Our proposed parallel implementation of a classical cyclic reduction algorithm to tackle the large linear systems arising from the discretized form of the elliptic problem at hand, schedules computing on both the GPU and the CPUs in a cooperative way. The experimental result demonstrates the effectiveness of this approach.     

Order Distance Estimation in Porous Glasses via Transformed Correlation Function of Small-Angle Scattering

A mesoporous two-phase system, consisting of colloidal silica in the cavities of the main silica frame work of a macroporous glass, was investigated by use of Small-Angle X-ray scattering. The transformed correlation function _T(r) was determined for this material for distances r<40 nm. The application of the intrinsic properties of _T(r) yields estimations for two fundamental order distances L ₁=11 nm and L ₂=120 nm of the~porous glass possessing a clear geometric interpretation: L ₁, a short-order-range, is the mean chord length of the mesopores plus the mean chord length in the secondary particles. L ₂, a long-order-range, is an estimation of the mean diameter of a macropore plus the mean free distance in the silica framework which separates two nearly parallel segments of two adjacent macropores.