Subsolidus Phase Relationships in Si3N4–AlN–Rare-Earth Oxide Systems

The subsolidus phase relationships in Si₃N₄–AlN–rare-earth oxide (Me₂O₃ where Me=Nd, Sm, Gd, Dy, Er, and Yb) systems were studied. Solid-solution regions with the α-Si₃N₄ structure were delineated along the Si₃N₄–"Me₂O₃:9AIN" joins for all of the rare-earth oxide systems studied. The solubility limits of these solid solutions increased with decreasing size of the rare-earth ions.     

Harnessing the Melting Peculiarities of Ultra‐High Molecular Weight Polyethylene Fibers for the Processing of Compacted Fiber Composites

Summary: Compacted fiber composites offer unique properties due to their lack of an extraneous matrix. The conditions of processing ultra‐high molecular weight polyethylene (UHMWPE) fibers were simulated in a heated pressure cell. In situ X‐ray diffraction measurements were used to follow the relevant transitions and the changes in the degree of crystallinity during melting and crystallization. The results strongly support the suggestion that the hexagonal crystal phase, in which the chain conformation is extremely mobile on the segmental level, constitutes the physical basis of compaction technologies for processing UHMWPE fibers into a single‐polymer composite. This report suggests that using a pseudo‐phase diagram outlining the occurrence of different phases during slow heating and the degree of crystallinity can provide valuable insight into the technological parameters relevant for optimal processing conditions.

Degree of crystallinity as a function of pressure and temperature in a region relevant to compaction processes.     

丙烯酸酯改性双环戊二烯酚型环氧树脂及其性能研究

通过FT－IR光谱表征了丙烯酸酯改性的DCPD酚型环氧树脂／DDM体系结构，并通过测定改性体系的凝胶时间和分析凝胶时间的影响因素，研究了该体系的反应特性，同时，对改造前后DCPD酚型环氧树脂体系的性能做了分析。     

灰色—支持向量机的空调负荷预测

对空调负荷进行准确预测不仅对空调优化控制的意义重大,而且也是实现空调经济运行与节能的关键所在。为了提高建筑空调负荷的预测精度,在分析灰色模型和支持向量机建模特点基础上提出了一种空调负荷组合预测算法。该方法综合了灰色建模计算过程简单以及支持向量机自学习和泛化能力强的优点,能够更加有效地利用样本数据的有效信息,提高模型预测精度。首先,通过灰色建模过程弱化了样本数据的随机因素。然后,对灰色模型输出进行归一化处理及数据重构,以作为支持向量机的输入。最后,通过支持向量机模型的预测得到最终预测结果。将本文所提出的方法应用于福州一栋办公建筑的逐时空调负荷预测中,并与灰色模型及支持向量机模型作比较,证明了组合模型的预测值与实际运行值拟合度最高,平均绝对误差比灰色模型和支持向量机模型分别降低了47.84%和17.39%。该组合预测模型具有较高的预测精度和更好的泛化能力,具有较强的可行性和实用性。     

基于CaO引导的甲烷蒸汽重整化学链燃烧制氢系统

为在重整气中得到高纯H_2和降低尾气CO_2分离成本,建立了基于CaO引导的甲烷蒸汽重整化学链燃烧制氢系统,该系统在重整反应器中加入CaO吸收剂,用以吸收重整器内的CO_2,提高重整气中H_2浓度,形成的CaCO_3固体在煅烧器中受热分解重新生成CaO。利用Aspen Plus进行了过程模拟及热力学分析,并研究主要参数对系统性能的影响,得到优化的操作条件为:CaO循环量/CH_4比为0.5,CH_4(燃料)/CH_4比为0.35,NiO循环量/CH_4比为1.4。CaO循环量/CH_4比从0变化到0.5时,重整气中H_2浓度从0.60增长到0.99;CH_4(燃料)/CH_4比在0.25~0.45区间变化时,重整气中H_2浓度从0.86提高到0.99,产气量增加;NiO循环量/CH_4比在1~1.6区间变化时,重整气中H_2浓度从0.88增长到0.99,系统有效能效率变化较小。     

Poly(trimethylene terephthalate) nanocomposite fibers comprising different organoclays: Thermomechanical properties and morphology

Poly(trimethylene terephthalate) (PTT) nano composites were synthesized by in situ polymerization at high temperature with two thermally stable organoclays: 1,2‐dimethylhexadecylimidazolium‐montmorillonite (IMD‐MMT) and dodecyltriphenyl phosphonium‐MMT (C₁₂PPh‐MMT). PTT hybrid fibers with various organoclay contents were melt‐spun at various draw ratios (DRs) to produce monofilaments. The thermomechanical properties and morphologies of the PTT hybrid fibers were characterized using differential scanning calorimetry, thermogravimetric analysis, wide‐angle X‐ray diffraction, electron microscopy, and mechanical tensile properties analysis. The nanostructure of the hybrid fibers was observed by both scanning and transmission electron microscopy, which showed that the clay layers were well dispersed into the matrix polymer, although some clusters or agglomerated particles were also detected. Unlike the hybrids containing IMD‐MMT, the clay layers of the C₁₂PPh‐MMT hybrid fiber were more dispersed into the matrix polymer. The thermal stability and tensile properties of the hybrid fibers increased with increasing clay content for DR = 1. However, as DR increased from 1 to 9 the ultimate strength and initial modulus of the hybrid fibers with IMD‐MMT increased slightly whereas those of C₁₂PPh‐MMT hybrid fibers decreased slightly. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 4535–4545, 2006     

分析用水对陶瓷铅溶出量测定的影响

分析用水水质对日用陶瓷铅溶出量测定具有重要影响,CL-、SO42-、CO2等严重抑制铅的溶出,使测定结果偏低。     

Contraction stress build‐up of anisotropic conductive films (ACFs) for flip‐chip interconnection: Effect of thermal and mechanical properties of ACFs

The important mechanical mechanism for the electrical conduction of anisotropic conductive films (ACFs) is the joint clamping force after the curing and cooling processes of ACFs. In this study, the mechanism of shrinkage and contraction stress and the relationship between these mechanisms and the thermomechanical properties of ACFs were investigated in detail. Both thickness shrinkages and modulus changes of four kinds of ACFs with different thermomechanical properties were experimentally investigated with thermomechanical and dynamic mechanical analysis. Based on the incremental approach to linear elasticity, contraction stresses of ACFs developed along the thickness direction were estimated. Contraction stresses in ACFs were found to be significantly developed by the cooling process from the glass‐transition temperature to room temperature. Moreover, electrical characteristics of ACF contact during the cooling process indicate that the electrical conduction of ACF joint is robustly maintained by substantial contraction stress below T_g. The increasing rate of contraction stresses below T_g was strongly dependent on both thermal expansion coefficient (CTE) and elastic modulus (E) of ACFs. A linear relationship between the experimental increasing rate and E × CTE reveals that the build‐up behavior of contraction stress is closely correlated with the ACF material properties: thermal expansion coefficient, glassy modulus, and T_g. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 2634–2641, 2004     

丙烯腈悬浮床催化水合制备丙烯酰胺的催化剂研究

考察了丙烯腈悬浮床水合制备丙烯酰胺的各种催化剂性能，研究了雷尼铜（Ｒａｎｅｙ Ｃｕ）催化剂的三种影响因素：铜铝成分的比例、冷却成型方式和添加组分的影响及催化剂的再生性能。结果表明：喷雾法制备的雷尼铜［Ａｌ∶Ｃｕ＝５２∶４８（质量比）］催化剂比普通雷尼铜催化剂活性高１０％，强度高２４％，并具有良好的再生性能，适于作为悬浮床催化剂     

基于边缘信息车流量检测方法的研究

针对边缘检测中阈值很难确定导致不能准确提取背景边缘信息的问题,提出一种改进的基于边缘信息车流量检测方法。该方法预先对路况边缘图像作削顶处理获取一个恰当的阈值,从而可以准确地提取背景边缘信息;且在车辆计数过程中,结合固定窗法和浮动窗法二者的优点,设计一种新的浮动窗法进行车辆计数。实验结果表明,该方法在实时性、检测速度、正确率等方面得到很大的改进,能够在不同环境下进行正确有效地车流量检测。