自动目标识别(ATR)算法评估研究综述

自动目标识别(ATR)算法评估是ATR研究领域的一项关键技术,已成为近年来该领域的一个热门课题.从ATR算法评估的国内外研究现状开始,对其常用的评估指标、典型的评估方法等进行了较为全面的分析和综述,在此基础上,比较了各种指标的优缺点,讨论了典型方法的适用范围,给出了主要研究结论,并提出了需要进一步解决的问题.     

一种基于ART2神经网络的算法改进

针对传统的ART2神经网络中对于主观设置的警戒参数以及识别分类过程中产生模式漂移的问题,提出基于改进算法的ART2神经网络模型,用于解决分析模式识别问题。通过自组织,加权,迭代等过程推导合理的警戒参数用于聚类运算,通过对ART2神经网络的权值训练方面进行修正,减缓学习速率,降低模式漂移速度,近一步对聚类对象进行合理分类。实验结果证明,该方法是可行的和有效的。     

一种高分辨雷达目标识别方法

研究了宽带高分辨雷达目标识别问题,基于目标一维距离像,提取目标散射中心特征,并根据该特征设计了简单目标的目标分类器,利用暗室测量得到的缩比模型高分辨回波数据进行识别,结果表明该识别方法具有良好的识别性能。     

基于知识的红外数字图像中铁路的识别

文中主要针对铁路红外图像的特点,在原有的自动目标识别算法上,将图像处理技术与人工智能相结合,提出一种基于知识的智能识别方法。采用先建立完善的结构知识库,再以知识库为基础,采用写生式策略来建立各种规则,并结合规则指导图像分割和特征提取,推断铁路的存在并指导铁路片断的连接,其基本思路可用于一般目标的识别。     

C60 LB单分子膜的电光Pockels效应

用电光调制衰减全反射光谱技术研究了Ｃ６０与花生酸混合的ＬＢ单分子膜的Ｐｏｃｋｅｌｓ（普克尔）效应。测量得到Ｃ６０ＬＢ膜的二阶非线性光学系数χ（２）（－ω;ω,０）＝０．５×１０－１２ｍ／Ｖ（１．３×１０－９ｅｓｕ）。这一结果与用光学二次产生测量Ｃ６０热蒸发膜的χ（２）（－２ω;ω,ω）同一数量级。并利用单分子层模型计算了Ｃ６０分子的超极化率为β＝１．１×１０－３０ｅｓｕ。     

Application of ATR-FTIR for a rapid and simultaneous determination of sugars and organic acids in apricot fruit

A simple, fast and accurate Fourier transform mid-infrared spectroscopy method was developed for simultaneously determining sugar and organic acid contents in apricot fruit slurries using the attenuated total reflectance. The potential of this method coupled with chemometric techniques based on partial least squares was assessed by comparison with currently used enzymatic determination of sucrose, glucose, fructose, malic acid and citric acid. Fruits of eight contrasted cultivars harvested at different ripening stages were used in this study and randomly divided in a calibration set (505 apricots) and in a validation set (252 apricots). The most suitable region was found in the range between 1500 and 900 cm⁻¹. Good prediction performances were obtained (R² ? 0.74 and RMSEP ? 18%). Results concerning the prediction of other quality traits such as firmness, skin colour, ethylene production, soluble solids content and titratable acidity were discussed.     

Preparation and characterization of 4A zeolite‐filled mixed matrix membranes for pervaporation dehydration of isopropyl alcohol

Sodium carboxymethylcellulose/poly (vinyl alcohol) mixed matrix membranes filled with different amounts 4A zeolite (0, 5, 10, 15, and 20 wt %) were prepared by solution casting method. Prepared membranes were crosslinked with GA and used for pervaporation dehydration of isopropyl alcohol of different feed mixtures at 35°C. On increment in zeolite content in the membrane it was found the improvement in the performance of the membrane, due to its hydrophilic nature and molecular sieving effect in addition to its favorable interaction with hydrophilic sodium carboxymethylcellulose and polyvinyl alcohol. The structure and chemical constituents of the MMM's were investigated by attenuated total reflectance Fourier transform infrared spectroscopy. Thermal stability of the membranes was assessed by DSC and TGA techniques. Crystallinity of the membranes was assessed using X‐ray diffraction, and the morphological properties were assessed by scanning electron microscopy. Mechanical properties were also carried out to determine the tensile strength and % of elongation at break using universal testing machine. It was found that the mechanical strength increases with increase in the zeolite content upto 15 wt % of zeolite with an optimum tensile strength of 113.31 N/mm². Pervaporation was carried out to asses the membrane performance, the highest flux and selectivity obtained is 0.584 kg/m²/h and 6945 for NaCMCA20 and NaCMCA15, respectively, for a feed composition containing 17.5 and 10 wt % of water in the feed and further swelling studies also supporting the pervaporation results. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Chemical modification of hemp fibers by silane coupling agents

Natural hemp fibers were chemically modified using silane coupling agents to reduce their hydrophilic character. The existence of a chemical bond between coupling agents and hemp fibers was confirmed by ATR‐FTIR spectroscopy, ²⁹Si Nuclear Magnetic Resonance (NMR), thermogravimetric analysis (TGA), energy dispersive spectroscopy (EDS), and BET surface area measurements. It was shown that the initial concentration and the chemical structure of the organosilane coupling agent have an effect on the grafted quantity on the hemp fiber surfaces. The grafted quantity increased proportionally to the initial concentration of silane molecules. The presence of polar amino end group (NH₂) in silane structure can cause an increase in the grafted quantity, compared with results obtained in the case of silane molecules containing methacryloxy groups. This effect is attributed to the formation of hydrogen bonds between NH₂ and unreacted hydroxyl groups of hemp fibers. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

硅橡胶泡沫伽马辐照后结构和元素分布研究

在密闭的氮气气氛下,用伽马射线辐照聚二甲基硅橡胶泡沫,采用全反射红外光谱(ATR)和X射线光电子能谱(XPS)对辐照后的化学结构和元素含量变化进行了表征.结果表明:化学结构单元Si-CH3最容易受到伽马射线的影响,在低的辐照剂量下表面Si-CH3成分随着辐照剂量增加而减小;高剂量下材料的元素分布发生了变化,近表面C元素含量要比泡沫体中部的C元素含量高.因此,在密闭环境下辐照老化后的硅橡胶泡沫的表面性能和体内性能存在差异.     

Orthogonal ligation to spherical polymeric microparticles: Modular approaches for surface tailoring

Modular ligation strategies for the functionalization of polymeric microspheres provide new perspectives for their applications in material science. In the current trend article we highlight variable synthetic procedures for generating functional microspheres via orthogonal modular conjugation chemistries. An overview of the different surface chemistries available is provided, followed by surface-sensitive characterization techniques relevant for the microparticles. Finally, we explore future trends in modular orthogonal modification approaches on microparticles and provide an outlook on the perspectives that the field of surface-modification of polymeric microparticles holds.