Investigation on the properties of a three‐component copolymer consisting of tris(allylphenoxy) triazine monomer and a diamine‐chain‐extension bismaleimide

A new type of modified bismaleimide resin was obtained by copolymerization between tris(allylphenoxy)triazine monomer (TAPT) and an aromatic diamine‐chain‐extension bismaleimide [e.g., 4,4′‐diaminodiphenylmethane (DADPM)‐chain‐extension 4,4′‐bismaleimidodiphenylmethane (BMDPM)]. The new three‐component‐polymer system had good processibility and mechanical properties. Better results were obtained when the weight ratio of TAPT to the DADPM‐chain‐extension BMDPM resin was 30%. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 475–480, 2004     

海河流域典型河流沉积物粒度特征及分布规律

为了解海河流域典型河流沉积物粒度参数空间分布规律,对海河典型河流的表层沉积物进行采集并利用Mstersize2000激光粒度仪进行粒度分析。结果表明,海河典型河流沉积物平均粒径差异显著,分选状况总体较差;山区水系与平原水系相比,沉积物平均粒径减小,呈集中分布,水动力减弱;山区自北向南变化明显,水系沉积物平均粒径减小,分布集中化,分选状况变差,由极正偏-正偏,向对称方向变化,峰度向平坦方向趋近,水动力减弱,符合粒径自然变化规律;平原区水系沉积物粒径参数表明南北变化不明显,因受较多支流、河流-湖泊-洼淀湿地等复杂系统和人为干扰强烈的影响,南北无显著变化规律。总的来说,海河流域河流受人为干扰强度较大,河流沉积物源较为复杂,栖息地物理完整性差。     

Discovering small-world in association link networks for association learning

Association Link Network (ALN) is a kind of Semantic Link Network built by mining the association relations among multimedia Web resources for effectively supporting Web intelligent application such as Web-based learning, and semantic search. This paper explores the Small-World properties of ALN to provide theoretical support for association learning (i.e., a simple idea of “learning from Web resources”). First, a filtering algorithm of ALN is proposed to generate the filtered status of ALN, aiming to observe the Small-World properties of ALN at given network size and filtering parameter. Comparison of the Small-World properties between ALN and random graph shows that ALN reveals prominent Small-World characteristic. Then, we investigate the evolution of Small-World properties over time at several incremental network sizes. The average path length of ALN scales with the network size, while clustering coefficient of ALN is independent of the network size. And we find that ALN has smaller average path length and higher clustering coefficient than WWW at the same network size and network average degree. After that, based on the Small-World characteristic of ALN, we present an Association Learning Model (ALM), which can efficiently provide association learning of Web resources in breadth or depth for learners.     

FAULT DIAGNOSIS OF HYDRAULIC SERVO SYSTEM USING THE UNSCENTED KALMAN FILTER

Fault occurrence can be embodied by the physical parameter variations of the hydraulic servo system. Faults can, therefore, be diagnosed according to the model coefficient variations of the hydraulic servo system. This paper proposes an approach for fault diagnosis based on the unscented Kalman filter (UKF) with a mathematical model of the hydraulic servo system. The mathematical model is established using the dynamic equations of the hydraulic servo system. Based on the fault mechanism analysis results, several important system model parameters that can separately represent different faults in different components of the hydraulic servo system are chosen. Discrete state space equations are derived from the dynamic equations. The UKF algorithm is used to estimate the important system model parameters of the hydraulic servo system by utilizing the discretized state space model. According to the variations of these model parameters, the fault modes and locations of the hydraulic servo system can be diagnosed and isolated. Two types of faults, namely, abrupt fault in servovalve gain and slow wear fault in hydraulic cylinder piston, which cannot be directly detected from the system output, are introduced individually to the hydraulic servo system in this work. By comparing with the extended Kalman Filter, three different experimental cases are used to validate the effectiveness of the UKF for hydraulic servo system fault diagnosis.     

三元不对称有机磷合成研究

三元不对称有机磷杀虫剂的良好药效已为人们所熟悉 ,而Ｐｒｏｆｅｎｏｆｏｓ的合成已有报导 ,他们采用了先合成ｓ -正丙基硫代磷酰二氯〔1〕的合成路线。作者以三氯硫磷为起始原料 ,经过与无水乙醇反应生成Ｏ -乙基硫代磷酰二氯〔4〕,然后将其依次与 2 ,4 -二氯苯酚钠、氢氧化钠及溴代正丙烷 (加入催化量的苄基三乙基氯化铵ＢＴＥＡＣ)反应 ,据软硬酸碱理论〔2〕,满意地得到了与预期符合的产物 (由红外光谱图中出现 ｐ =0而证实 ) ,即Ｏ -乙基 -Ｏ -2 ,4 -二氯苯基 -ｓ -正丙基硫醇代磷酸酯 (Ⅰ )杀虫剂 ,该化合物与Ｐｒｏｆｅｎｏｆｏｓ(Ⅱ…     

求强规划解的快速状态分层算法

在求强规划解时,通过状态分层可以大幅减少问题规模,提高搜索效率,并能得到规划路径较短的强规划解。但现有分层算法本身有一定的复杂度,在状态较多时开销较大。为此,通过改进已有分层算法,设计一种适用于求强规划解的快速状态分层算法。采用链式双向图结构保存数据,在分层时修改已遍历的状态动作序偶,并根据修改结果直接进行分层判断,使得分层时只需要判断前一层状态而不是所有已分层状态,避免对非必要状态转移的搜索以及对必要状态转移的重复搜索。实验结果表明,该算法的分层速度优于已有的矩阵乘分层算法。     

基于证据理论的陶瓷智能感观评估

陶瓷感官评估结果的表达形式包括语言词汇、象征性符号和数值描述等，它们具有不确定性和不精确性。本文首先运用模糊逻辑技术对这些评估结果定量化，并基于证据理论提出了一种陶瓷智能感观数据融化方法，得到了基于感观数据的质量分级，并取得了较好的实验结果。     

Effect of montmorillonite on properties of styrene–butadiene–styrene copolymer modified bitumen

Clay/styrene–butadiene–styrene (SBS) modified bitumen composites were prepared by melt blending with different contents of sodium montmorillonite (Na‐MMT) and organophilic montmorillonite (OMMT). The structures of clay/SBS modified bitumen composites were characterized by XRD. The XRD results showed that Na‐MMT/SBS modified bitumen composites may form an intercalated structure, whereas the OMMT/SBS modified bitumen composites may form an exfoliated structure. Effects of MMT on physical properties, dynamic rheological behaviors, and aging properties of SBS modified bitumen were investigated. The addition of Na‐MMT and OMMT increases both the softening point and viscosity of SBS modified bitumens and the clay/SBS modified bitumens exhibited higher complex modulus, lower phase angle. The high‐temperature storage stability can also be improved by clay with a proper amount added. Furthermore, clay/SBS modified bitumen composites showed better resistance to aging than SBS modified bitumen, which was ascribed to barrier of the intercalated or exfoliated structure to oxygen, reducing efficiently the oxidation of bitumen, and the degradation of SBS. POLYM. ENG. SCI., 47:1289–1295, 2007. © 2007 Society of Plastics Engineers     

现代陶艺的特异性

现代陶艺集雕塑语言与绘画语言于一体,加上陶瓷工艺的神奇功效而形成现代陶艺特有的艺术语言,陶艺已成为现代艺术家喜爱的最富特色和最具活力的艺术创作形式之一。本文就现代陶艺的随意性,创造性,工艺性谈谈现代陶艺的特异性。     

SSI:一种IPv6/IPv4多址同源识别模型

IPv6/IPv4共存环境下多址同源识别是共存网络管理与拓扑发现的一个关键问题。现有研究主要集中于子网内部的双栈发现及单一IP协议栈中的别名解析,难以识别远程IPv6/IPv4共存网络中的多址同源。通过分析同源地址间的本质联系,提出一种IPv6/IPv4多址同源识别模型(SSI),该模型综合利用特殊地址格式匹配、TCP时钟指纹比对和上层协议短时致瘫等多种方式来提高同源地址的识别能力。实验结果表明,上述方法均可有效识别IPv6/IPv4多址同源;SSI模型具有较理想的识别率和正确率。