Enhancement of radiation‐resistant effect in ethylene–vinyl acetate copolymers by the formation of ethylene–vinyl acetate copolymers/clay nanocomposites

Ethylene–vinyl acetate (EVA) copolymers/clay nanocomposites, prepared by using nonreactive organophilic clay and reactive organophilic clay, were characterized by X‐ray diffraction and by high‐resolution transmission electron microscopy. The influence of gamma irradiation on the structure and properties of the pure EVA and EVA/clay nanocomposites was systematically investigated. In the presence of gamma radiation, the clay can effectively restrain the increase of the storage modulus of EVA/clay nanocomposites, which was supported by dynamical mechanical analysis. Gamma irradiation had almost no effect on the thermal properties of EVA/clay nanocomposites by using nonreactive organophilic clay, but it obviously improved the thermal stability of EVA/clay nanocomposites by using reactive organophilic clay. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 2532–2538, 2005     

支持跨步访问的嵌入式存储系统

提出了一种新型多素数嵌入式存储系统,能够显著改善系统跨步访问的性能。提高跨步访存的带宽,对于改善系统的整体性能有着重要的意义。但是,在嵌入式系统中,受片外结构的尺寸限制,直接应用经典的素数存储系统理论无法显著改善跨步访存性能。为此,该新型系统以素数存储系统理论为基础,引入主存访问调度策略并结合嵌入式系统的实际结构特征,构造了一种两层结构的多素数存储系统,可以用较少数量的存储模块实现,而且从逻辑地址到物理地址的映像计算简单,能够以相对较小的硬件代价实现对嵌入式存储系统跨步访问的有效支持。理论分析和实验结果均证实了该系统的正确性和有效性。     

高选择性低汽气比一氧化碳低温变换催化剂的研究

实验室试验表明,添加助剂的低汽气比一氧化碳低温变换催化剂,在保证活性和稳定性的基础上,明显地提高了选择性,其甲醇生成量可降为原来的1/4左右。     

基于淘宝直通车的竞价决策系统的研究与设计

电子商务蓬勃发展的大环境下,广告主具有强烈的电商广告投放意愿,显然他们并未达到电商广告的核心业务SEM （搜索引擎营销优化）的专业要求。所以广告主希望借助第三方工具来进行搜索引擎广告投放的一站式服务来满足其业务需求。基于此,本文将提供一整套的竞价词托管式服务的解决方案。以淘宝直通车这一全新的搜索竞价模式作为研究对象,从语义抽取、关键词扩展、竞价词生成、模型化出价、广告效果正向反馈监控模型几方面进行分析和统计,为直通车广告主提供最优投放策略整体解决方案。第一阶段针对商品信息进行数据挖掘,实现关键词推荐引擎。第二阶段实现投放优化模块,实施定价策略,建立的点击量与PPC（“平均点击花费”）模型,实现在预算资金的约束下对不同竞价组合进行ROI（投入产出比）最大化的投资决策。以实际效果改善直通车竞价搜索用户体验。     

Supramolecular complexes: lamellar structure and crystalline transformation

Interfacial reaction of highly-branched polyethyleneimine (PEI) with octadecanoic acid (OA) was performed to prepare a series of supramolecular complexes (PEI(OA)_x). The complexes at solid state have typical lamellar structure, and the interlamellar distance can be modulated by the OA content. The long period values of the supramolecular complexes measured by SAXS were found to be dependent on the compositions, which are in good consistency with those measured by TEM. For example, the long period values from SAXS for PEI(OA)_0.76, PEI(OA)_1.03, and PEI(OA)_1.67 were 46.5, 62.7, and 56.2 Å, respectively. The corresponding data from TEM were 45.7, 60.7, and 56.6 Å, respectively. A model was proposed for the construction mode of the side alkyl chains (crystallization region) associated with PEI backbone (amorphous region), in which the side alkyl chains were arranged to be ‘end-to-end’ packing for the x=1 complex, while an ‘interdigitated structure’ of the side alkyl chains was deduced for the x>1 and x<1 complexes. Temperature variable FT-IR combination investigation of the scissoring band, rocking band, and stretching band of methylene (CH₂) and vibrational band of carbonyl group (CO) indicated that the crystalline form of the crystallization region in the lamellae can be transformed from orthorhombic to hexagonal with the temperature increasing, and vice versa.     

乙烯装置三机的自动控制系统

系统地介绍乙烯装置三机的自动控制系统，包括油系统、气系统和工艺系统的控制，并对运行以来发生的主要故障进行了分析，最后对控制系统发展的前景进行了展望。     

Biomorphic Silicon Nitride Ceramics with Fibrous Morphology Prepared by Sol Infiltration and Reduction–Nitridation

Biomorphic silicon nitride (Si₃N₄) ceramics with fibrous morphology were fabricated by combining sol–gel infiltration with carbothermal reduction nitridation from wood precursor. Y₂O₃-incorporated silica sol was used as the infiltrated solution to promote the formation of fibrous Si₃N₄ grain at 1600°C under high nitrogen pressure (0.6 MPa). The influence of sintering conditions (additive and temperature) on the phase composition and microstructure of sintering bodies was analyzed, and the reaction mechanism is discussed.     

混炼胶门尼粘度的预测与控制

使用ＭＧＫＪ型密炼机混炼微机监控系统，在ＢＢ２７０型密炼机上预测混炼胶的门尼粘度值，实现了胎面胶门尼粘度值的预测。预测值与实测值的差平均为０８（相对误差１％）。借助预测门尼粘度的数学模型，对排胶点进行控制，使混炼胶门尼粘度的波动范围为－３～＋３。     

改进教与学优化算法的LQR控制器优化设计

为了快速有效地确定线性二次最优控制(linear quadratic regulator,LQR)问题中的加权矩阵Q和R,针对主动悬架LQR控制器权系数设计问题,提出一种改进的教与学优化算法进行LQR优化设计。算法对基本教与学优化算法中的"教"与"学"阶段进行了进一步的改进,同时提出一种"自我学习"策略。通过仿真实验表明,和基本教与学算法、粒子群算法、遗传算法相比,本文算法在对主动悬架LQR控制器优化时,具有收敛速度快,求解精度高和稳定性强等优势。     

分离技术的进展

本文概述了基于生物技术的发展、超纯材料的制备等对发展分离科学和技术的需求,特别是从大量基体物或稀溶液中提取、分离、纯化和检测低含量物质要求发展高选择性的分离技术和相应的分离体系。在发展和完善原有分离技术(如萃取、离子交换、吸附、吸收等)的同时,超临界萃取和膜分离技术具有引入的应用前景。还应注意两种或多种分离技术相结合的分离方法和技术的研究。