基于参数化分位回归模型的非寿险准备金评估

准备金及其风险边际对保险公司的偿付能力具有决定性影响.均值回归模型在非寿险准备金评估中的应用较为普遍,但需要通过Bootstrap等方法计算准备金的风险边际.分位回归模型可以一次性求得准备金及其风险边际的预测值,所以在非寿险准备金评估中具有独特的应用价值.基于GB2(Generalized Beta type 2)分布建立了一种参数化分位回归模型,该模型首先对GB2分布中的位置参数和尺度参数同时引入流量三角形数据中的事故年和进展年作为解释变量,增加了模型的灵活性;其次,根据模型参数的极大似然估计结果,借助分位数函数的表达式,计算了不同分位数水平下的准备金预测值;最后,利用极大似然估计的渐近性质,通过Delta方法给出了准备金预测值的误差.基于一组增量赔款数据的实证研究结果表明,GB2参数化分位回归模型在非寿险准备金评估及其风险边际的预测中具有良好的应用价值.     

Patterning the neuronal cells via inkjet printing of self-assembled peptides on silk scaffolds

The patterning of neuronal cells and guiding neurite growth are important for neuron tissue engineering and cell-based biosensors. In this paper, inkjet printing has been employed to pattern self-assembled I₃QGK peptide nanofibers on silk substrates for guiding the growth of neuron-like PC12 cells. Atomic force microscopy (AFM) confirmed the dynamic self-assembly of I₃QGK into nanofiber structures. The printed self-assembled peptide strongly adheres to regenerated silk fibroin (RSF) substrates through charge-charge interactions. It was observed that in the absence of I₃QGK, PC12 cells exhibited poor attachment to RSF films, while for RSF surfaces coated or printed with peptide nanofibers, cellular attachment was significantly improved in terms of both cell density and morphology. AFM results revealed that peptide nanofibers can promote the generation of axons and terminal buttons of PC12 cells, indicating that I₃QGK nanofibers not only promote cellular attachment but also facilitate differentiation into neuronal phenotypes. Inkjet printing allows complex patterning of peptide nanofibers onto RSF substrates, which enabled us to engineer cell alignment and provide an opportunity to direct axonal development in vitro. The live/dead assay showed that printed I₃QGK patterns exhibit no cytotoxicity to PC12 cells demonstrating potential for future nerve tissue engineering applications.     

Carbon-free nanoporous gold based membrane electrocatalysts for fuel cells

Nanoporous gold (NPG) membranes made by dealloying consist of a bicontinuous network of Au ligaments and open pore channels, which have gained considerable attention as a platform for the design of carbon-free electrodes for proton exchange membrane fuel cells (PEMFCs). Benefiting from a unique combination of high electronic conductivity, high surface area, and modifiable surface chemistry, these self-supporting membrane type electrodes allow integration of various structural functions required for specific electrode reactions and simultaneously facilitate the entire fuel cell kinetic process. In this review, we summarize the major research progresses in this area, with an emphasis on how to customize the surface structures of these three-dimensional electrocatalysts for desired fuel molecule oxidation and oxidant reduction. We will also discuss these designed structural characteristics that can be readily accommodated in membrane electrode assemblies (MEA), thus effectively bridging the technological gap between electrocatalysts’ intrinsic activities and their actual performances in fuel cells.     

Notes on types of Australian Chartocerus Motschulsky (Hymenoptera: Signiphoridae)

ABSTRACT

Type specimens of 11 species of Chartocerus (Hymenoptera: Signiphoridae) from Australia described by A.A. Girault, in the collection of the Queensland Museum, and one species described by W.H. Ashmead, in the United States Museum of Natural History, are redescribed and illustrated. Lectotypes are designated for Chartocerus australiensis (Girault) and Chartocerus hebes (Girault).     

海洋钻井平台塔型井架安装方式探讨

由于海洋钻井的复杂环境和作业条件,要求海洋钻井井架结构具有强度高、稳定性高、底部开档大及良好的司钻视野等特点,大多选用塔型整体结构井架。因资源、环境条件、工期及施工费用等因素,塔型井架在钻井平台上的安装是一个复杂的课题。针对可能的塔型井架安装方案,通过分析各种影响因素,提出井架分段吊装的方式,并成功应用于海洋石油281平台,为后续钻井平台塔型井架安装提供了作业借鉴。     

联系一些特殊函数的Hilbert型积分不等式及其算子范数表达式

利用权函数方法、实分析技巧和特殊函数的相关理论,建立一个多参数的联系一些特殊函数的Hilbert型积分不等式及其等价式,证明其常数因子是最佳的,并给出其算子范数的表达式.     

高速实时可见光通信技术研究及应用

 介绍了可见光通信技术的发展历史及研究现状。基于带宽拓展技术搭建了1 W荧光型LED做光源、PIN光电二极管做探测器、单路速率610 Mb/s的实时传输演示系统，该系统在传输距离为6.2 m时的误码率为3.48×10^-5。在此基础上搭建了荧光型LED为光源、PIN光电二极管做探测器的、双向100 Mb/s无线光上网演示系统。     

基于改进离散粒子群算法构建制造单元

在未知最佳分群单元数的情况下,考虑了零件多种可选工艺路径和零件工艺顺序,建立基于最小化零件跨单元移动次数的数学模型.通过引入自适应变异因子,提出一种改进的离散粒子群优化算法能动态地确定分群单元数,极大地减少了算法陷入局部最优解的可能.通过对文献中不同规模的单元构建问题进行求解,结果证明了该方法有效,并且无需预先设定分群单元数即可获得与文献中相同甚至更好的结果.     

齐次核的Hilbert型多重级数不等式取最佳常数因子的等价条件及应用

利用实分析技巧和权函数方法, 讨论具有齐次核的多重级数Hilbert型不等式, 得到了其取最佳常数因子的充分必要条件, 并给出其应用.     

微生物燃料电池修复钒污染地下水的响应曲面优化研究

使用响应曲面法, 对单室微生物燃料电池去除五价钒的运行条件进行分析和优化。采用乙酸钠作为单室微生物燃料电池的碳源, 探讨钒初始浓度、COD初始浓度和电解液电导率对五价钒去除率的影响, 三因素三水平的响应曲面分析结果表明, 五价钒初始浓度对五价钒去除率的影响最显著, 其次为 COD 初始浓度, 最后是电解液电导率。利用响应曲面法得到最优实验条件: 五价钒初始浓度为75.44 mg/L, COD初始浓度为1007.48 mg/L, 电导率为11.98 mS/cm, 此时可获得五价钒的最大理论去除率80.31%。验证实验的结果证实了该优化方法的可靠性。研究成果可以促进微生物燃料电池技术在治理钒污染地下水领域的实际应用。