Characterization of ramie yarn treated with sodium hydroxide and crosslinked by 1,2,3,4‐butanetetracarboxylic acid

Ramie yarns were treated with various concentrations of NaOH at room temperature and subsequently crosslinked with 1,2,3,4‐butanetetracarboxylic acid (BTCA). The microstructure and tensile properties of the treated yarns were characterized. X‐ray diffraction (XRD) and FTIR were used to study the crystalline structure of the resultant ramie yarns. The results showed that the maximum change in the structure of the alkali‐modified ramie took place at 16% NaOH, which would completely transform cellulose I to cellulose II. At the same time, the crystallinity index and fiber orientation decreased to the minimum value while the absorption properties were enhanced. The average degree of polymerization (DP ) of the treated ramie yarns slightly decreased after NaOH treatment. Tensile properties including tenacity, breaking elongation, and modulus of the treated yarns were also investigated. Scanning electron microscopy (SEM) was used to investigate the breakage of the treated yarns. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 1857–1864, 2004     

玉米芯木聚糖硫酸酯化条件的研究

用碱提法从玉米芯中提取木聚糖,采用氯磺酸吡啶法进行硫酸酯化,通过正交试验确定最佳工艺条件为:吡啶与氯磺酸摩尔比1∶1,温度65℃,时间6h;木聚糖硫酸酯wisX-S通过DEAESepharoseFF层析柱分离得到一个相对分子量为1.3×104的组分,硫酸基取代度为2.24。对此木聚糖硫酸酯进行红外光谱分析,结果显示在波数1259、1228和813cm-1处分别有S=O和C-O-S键的特征吸收峰。     

基于Monte Carlo随机模拟的综合交通网络布局评价与决策方法

针对综合交通网络评价指标权重及属性值具有主观性和随机性的特点,提出了基于模拟运算的布局规划方案排序选优的群体随机决策方法.仿真生成满足集结的多个专家对指标重要性偏好排序统计分布的权重,同时考虑交通需求的不确定性对指标值的影响,结合客观熵权计算方案的综合评价值,由多次模拟得到的排序优势度确定方案的优劣差异.根据设计的仿真流程通过算例说明了方法应用的有效性,评价中考虑了主客观因素及随机性特征,可以为网络布局提供科学决策依据.     

复杂体制雷达辐射源信号特征的集对分析

为解决复杂体制雷达辐射源信号特征的评价问题,提出了基于集对分析理论的复杂体制雷达辐射源信号特征分析模型.首先对复杂体制雷达辐射源信号特征评价指标体系的指标权重作层次分析,再通过集对分析理论对复杂体制雷达辐射源信号特征评估的决策矩阵进行同一度分析,最后联合指标权重矩阵和决策同一度矩阵对复杂体制雷达辐射源信号特征进行综合评判.仿真结果表明,该模型是有效、可行的,能够更好地实现对复杂体制雷达辐射源信号特征的分析和评估.     

基于有限状态自动机的人眼开度PERCLOS实现算法

针对驾驶员驾驶过程中因疲劳引起的眼睛开度变化问题, 在原有PERCLOS(percentage of eyelid closure over the pupil over time)标准的基础上, 提出了一种基于有限状态自动机的人眼开度PERCLOS计算方法, 并将其应用到疲劳驾驶预警系统中。该系统首先采用红外摄像头实时获取驾驶员的脸部视频图像, 使用ASM(active shape models)算法进行人脸检测, 在定位到的人脸范围内搜索人眼区域并计算人眼开度, 为了避免人与摄像头距离变化影响计算结果, 对人眼开度进行归一化处理; 然后依据建立的有限状态自动机模型计算PERCLOS值; 最后根据制定的预警机制实现基于人眼开度的疲劳预警。实验结果表明本方法能够实时监测驾驶员疲劳状况, 具有对光照变化、脸部配饰不敏感的特点。     

PVC-U异型材塑化度的评价

比较了4种评价PVC-U塑化度的方法:目测法简单;溶剂法迅速,容易操作;拉伸法可定量判断,但需要大量样品;DSC法准确、方便。     

基于像素点的碎片图像拼接技术

针对一页规则的既纵切又横切的中文文件碎片和一页规则的双面打印的英文文件碎片,分别提出了一种基于行列图像的碎片匹配算法和二维图像成片连接匹配算法。首先将碎片边缘像素点转化成灰度值,然后对各碎片的灰度值进行匹配度研究,且将匹配度作为碎片之间拼接的依据,最后使用相应的算法计算机按碎片拼接顺序输出碎片号。通过实验分析表明,该算法能够更快地获得碎片拼接结果,大大提高拼接复原效率。     

变精度软粗糙集

从集合间的包含程度出发,构造了一种基于包含度的变精度软粗糙集模型。提出带参数的变精度近似算子的定义,得到了它的基本性质和定理,并给出了证明;定义了双精度软粗糙集的近似算子,研究了其性质;讨论了该模型与其他粗糙集模型的关系以及退化条件;举例说明了在信息处理中的应用。     

Effect of Ammonia on Silicone Rubber-Glass Adhesion

The adhesion energy between silicone rubber and glass has been obtained from the Johnson, Kendall and Roberts' test. The specific effect of ammonia on the quasi-equilibrium value has been studied as a function of the degree of crosslinking of the elastomer. For PDMS networks with lower molecular weight between crosslinks, the effect is more pronounced but completely reversible. This has been related to the increase in the non-dispersive part of the surface energy of the silicone due to the imbibed ammonia. In incompletely crosslinked hydroxyl-terminated PDMS, ammonia has a catalytic effect and is responsible for chemical bonding between the unreacted hydroxyl groups of the PDMS and the hydroxyl groups on glass.     

聚醋酸乙烯酯树脂聚合度的快捷检测方法

通过实验得出不同聚合度、不同质量分数下的黏度数据，并作出平均聚合度-质量分数-黏度三者的关系曲线。在此基础上，提出通过检测聚醋酸乙烯酯树脂的质量分数和黏度，直接查出对应的聚合度的快速检测方法。