Escrow-Free Certificate-Based Authenticated Key Agreement Protocol from Pairings

Key agreement protocols are essential for secure communications. In this paper, to solve the inherent key escrow problem of identity-based cryptography, an escrow-free certificate-based authenticated key agreement （CB-AK） protocol with perfect forward secrecy is proposed. Our protocol makes use of pairings on elliptic curves. The protocol is described and its properties are discussed though comparison with Smart＇s protocol.     

Palaeolake and palaeoenvironment between 42 and 18 kaBP in tengger desert, NW China

Comprehensive field investigations and laboratory analyses show that palaeolakes, including fresh- mesohaline water Megalake Tengger and other semi-con- nected, isolated water bodies, during late Pleistocene covered an area of more than 20000 km², which is more than half of the Tengger Desert in NW China. Stratigraphic correlation and chronological evidence indicate that before ca. 42000 aBP the area was more arid. The palaeolakes started to develop around 40000 uncal. ¹⁴C aBP but until 37000 ¹⁴C aBP their scope was limited. High water levels established from 35000 ¹⁴C aBP lasted until 22000 ¹⁴CaBP. Lake levels regressed between 22000 and 20000 ¹⁴C aBP but transgressed from 20000 to 18600 ¹⁴C aBP. Subsequently, water level declined further and the Megalake Tengger finally desiccated at around 18000 ¹⁴C aBP. Megalake Tengger possessed a fresh-mesohaline water property, implying that the regional precipitation increased significantly. During the period of Megalake Tengger, the climate was warmer-humid than present. The annual rainfall was 250 to 350 mm more than that of today and the temperature was 1.5 to 3.0℃ higher.     

The ecological sequence of Hipparion fauna in the mid-dle reaches of the Yellow River during Neogene

The faunal ecological type and sequence in the Tertiary red clay indicate that Hipparion fauna during the period 7.4-6.1 Ma in the middle reaches of the Yellow River is composed mainly of dorcadoides and mixed types. This represents semiarid veld environment with small fluctuation. The fossil assemblages characterized by the abundance of gaudryi types and even the occurrence of some Hominoid and Chalicotherium indicate an obviously warm and humid period since 5.3 Ma. The fossil assemblages during 3.4 Ma show the typical steppe fauna representing dry climate. It is indicated by the changes of ecological sequence that the climatic conditions in Pliocene are drier than that in late Miocene. The clay-skin content of red clay, which has a synchronous change with faunal features, is a rather good replacing palaeoclimatic index.     

The ecological sequence of Hipparion fauna in the middle reaches of the Yellow River during Neogene

The faunal ecological type and sequence in the Tertiary red clay indicate that Hipparion fauna during the period 7.4–6.1 Ma in the middle reaches of the Yellow River is composed mainly of dorcadoides and mixed types. This represents semiarid veld environment with small fluctuation. The fossil assemblages characterized by the abundance of gaudryi types and even the occurrence of some Hominoid and Chalicotherium indicate an obviously warm and humi period since 5.3 Ma. The fossil assemblages during 3.4 Ma show the typical steppe fauna representing dry climate. It is indicated by the changes of ecological sequence that the climatic conditions in Pliocene are drier than that in late Miocene. The clay-skin content of red clay, which has a synchronous change with faunal features, is a rather good replacing palaeoclimatic index.     

波分复用器件自聚焦透镜耦合系统的优化设计

利用光纤矩阵方法和高斯光学的耦合损耗理论，对波分复用器件的自聚焦透镜耦合系统进行了分析，得出了一种优化设计耦合系统的分析和计算方法。结合计算结果的曲线，分析了耦合系统中透镜长度对耦合损耗的影响，提出了通过调整入射单模光纤与自聚集透镜粘接的角度来减小耦合损耗的新方法。     

关于改善缆道吊箱提升用力的研究

缆道吊箱是中小河流上测取洪水流量的测流设备，就如何减轻吊箱在使用中的提升用力，如何解决好吊箱升速大于洪水上涨速度等问题做了实质性的论述，并在实践中得到验证。收效甚好。     

活性炭纤维与柱状活性炭用于烟气脱硫的对比实验

在活性炭法烟气脱硫工艺中，为了有效地提升系统运行的综合性能，通过实验将活性炭纤维（ACF）与普通的柱状颗粒活性炭（GAC）的各项特性进行了对比，实验结果表明，在同样的工作条件下，ACF的吸附系数比GAC提高16．6倍，损耗减少到GAC的1／14，脱附效率棕达一99．8％以上，证明了采用ACF作为工质可以大大送还和吸附剂用量，显著降低补充新工质的次数，减少设备的投资和运行费用，因而使活性炭法烟气脱硫系统在运行的经济性，可靠性和持久性方面均具有比较明显的优势。     

低体积收缩率光固化树脂的研究

针对目前所使用的自由基型紫外光固化树脂体系的体积收缩率较大的问题 ,采用一种新型的大相对分子质量齐聚物与环氧丙烯酸酯齐聚物混合 ,通过优化配方 ,得到体积收缩率分别为5 4 %和 5 7%的两种高性能光固化树脂 ,在 30℃时它们的粘度分别为 360mPa·s和 5 2 0mPa·s ,而且均具有较高的固化速度和拉伸强度 .     

静载作用下波形梁的非线性数值分析

通过对波形梁在静载作用下的行为进行非线性分析（材料和几何均非线性），归纳和总结了波形梁的几何变形特点，同时还研究了各类变形所对应的能量变化规律，数值分析结果与实验结果的对比表明，它们有良好的一致性，这说明本文中的FEM数值分析方法是可行的。