大坝安全信息权研究

大坝原型观测数据本身包含了丰富的信息，内在反映了监测项目之间的某种客观关系，基于此，应用PCA法及PPA法建立了确定大坝安全评价信息权重的正分析模型，一方面能够对数据进行降维处理，另一方面能挖掘数据内在信息，提取指标的相对重要性；并基于最优化准则，建立了信息赋权整合模型，解决了多种数学方法计算结果不一致性问题，最大限度地保持原始信息的完整性。     

过磷酸（SPA）可用作柏木烯乙酰化作用的催化剂

本文论述经实验和四年多出产实践证明 ,过磷酸 (SPA)可用作柏木烯乙酰化作用的催化剂。在甲基柏木酮(MCK)合成工艺中 ,与多聚磷酸 (PPA)催化剂相比 ,过磷酸有直接使用和方便之优点 ,并能改善劳动条件 ,而且过磷酸催化剂的成本略低于多聚磷酸催化剂     

Evaluation of polyphosphoric acid on the performance of polymer modified asphalt binders

The aim of this research is to evaluate the effect of polyphosphoric acid (PPA) on the mechanical performance of styrene–butadiene–styrene (SBS) and styrene–butadiene–rubber (SBR) modified asphalt. Conventional properties, multiple stress creep recovery (MSCR), bending beam rheometer (BBR), and linear amplitude sweep (LAS) tests were conducted to evaluate the performance characteristics of asphalt at different PPA inclusions. Gel-permeation chromatography (GPC), saturates, aromatics, resins, and asphaltenes (SARA), and Fourier transform infrared (FTIR) were carried to reveal the molecular weight, component and infrared spectra of asphalt. Results showed that PPA hardened the asphalt, improved the rutting and fatigue performances of polymer modified asphalt (PMA) binder, but weakened the anti-cracking performances. Besides, storage stability had a significant improvement as the addition of PPA. The addition of PPA brought more macromolecules into asphalt and led to more high-average molecular weight compounds. Furthermore, PPA changed four component ratios of asphalt. Both PMA with or without PPA have similar absorption peaks. This may be due to absorption peak of PMA covered the changes in PPA modification process as the low content of PPA. 0.8% dosage of PPA may be considered optimum for composite modified binder combining the above experimental results for this binder source.     

北京奥林匹克公园网球场场地照明设计

本文将国内外网球场地照明设计标准进行综合分析和整理，介绍了国家网球中心场地照明的设计。     

PPA多元醇相对分子质量测定的影响因素

概述了聚己二酸-1,2-丙二醇酯多元醇的几种相对分子质量的估算方法,讨论了这几种估算方法产生误差的原因和消除误差的对策。     

Silicate-based polymer-nanocomposite membranes for polymer electrolyte membrane fuel cells

Proton-exchange membrane fuel cells have emerged as a promising emission free technology to fulfill the existing power requirements of the 21st century. Nafion^® is the most widely accepted and commercialized membrane to date and possesses excellent electrochemical properties below 80 °C, under highly humidified conditions. However, a decrease in the proton conductivity of Nafion^® above 80 °C and lower humidity along with high membrane cost has prompted the development of new membranes and techniques. Addition of inorganic fillers, especially silicate-based nanomaterials, to the polymer membrane was utilized to partially overcome the aforementioned limitations. This is because of the lower cost, easy availability, high hydrophilicity and higher thermal stability of the inorganic silicates. Addition of silicates to the polymer membrane has also improved the mechanical, thermal and barrier properties, along with water uptake of the composite membranes, resulting in superior performance at higher temperature compared to that of the virgin membrane. However, the degrees of dispersion and interaction between the organic polymer and inorganic silicates play vital roles in improving the key properties of the membranes. Hence, different techniques and solvent media were used to improve the degrees of nanofiller dispersion and the physico-chemical properties of the membranes. This review focuses mainly on the techniques of silicate-based nanocomposite fabrication and the resulting impact on the membrane properties.     

户外全彩显示SMD器件设计要点分析

贴片式SMD全彩器件具有视角广、配光好、混光佳、对比度高的优势。本文分析了PPA材料对SMD全彩器件的影响,简要说明了SMD全彩器件防湿设计要点。我们的技术开发实践证明,只要通过合理的防湿设计,可以解决SMD全彩器件在户外高湿环境中的可靠性问题。     

连续长碳纤维增强PPA的制备及性能的研究

设计和制备了高温尼龙(PPA)熔融浸渍碳纤维装置,用熔融浸渍法制备长碳纤维增强PPA复合材料(LFPPA).主要研究了长碳纤维增强PPA的浸渍工艺条件与材料性能之间的关系.分别研究了不同熔体质量流动速率(MFR)、浸渍槽浸渍温度、浸渍时间等浸渍工艺对长碳纤维增强PPA性能的影响.提高浸渍温度与延长浸渍时间都可以提升浸渍效果,增强复合材料的拉伸性能.     

浅议EMC在LED封装中的应用

环氧模塑料（EMC）作为一种常见的封装材料,具有可规模化生产和高可靠性等特点,被广泛应用于微电子封装领域。随着LED半导体照明技术的迅速发展,EMC作为一种新型支架塑封材料被引入到LED封装行业,成为第三代LED封装支架。与传统的PPA材料相比,EMC具有低膨胀系数、高热导率、更好的耐热性等优势。由于EMC支架是一种高度集成化的支架,具备更好的封装性能和可靠性,可进一步提升LED器件的可靠性并降低LED器件的成本。文章主要介绍EMC支架的主要特点、优势及其制作工艺,同时也总结了EMC在LED封装应用过程中还存在的一些问题。