低温管路预冷过程的实验研究

搭建了低温管路预冷过程实验台,并对不同管长和不同入口压力下低温管路预冷过程中压力和温度的变化情况进行了实验研究。结果表明,管路较长时,不稳定现象表现得更加剧烈,管路预冷时间变长,并会产生更大的压力峰值。     

随机意外大灾风险模型的破产概率

论文针对现实生活中存在非同质性意外大额赔付的情况,在更新风险模型的基础上,进一步建立广义更新风险模型,给出了在有意外大额赔付情况下保险公司破产概率的尾等价式,此结果表明了突如其来的大额索赔可能会导致保险公司破产.     

一类重灾风险模型的生存概率

无法预料的索赔是导致保险公司破产的一大因素,这种情况引起的索赔大多不是同分布的.因此论文从这一实际情况出发,在Sparre Andersen风险模型的基础上建立了广义更新风险模型,并对重尾索赔分布F∈S*给出了生存概率的局部等价式和破产概率的尾等价式.文章结果刻画了特殊巨额索赔对公司运营状况的影响,对公司运营策略提供了理论基础.本文结果包含、推广并改进了许多已知结果,与经典结果相比,显示出了模型的优越性.     

中国B股市场指数长程参数的估计及其应用

本通过对中国B股市场指数2001年2年前后历史数据的处理，给出了指数维数的R/S估计。所得结果显示HURST维数是用来反映时常波动的合理的数理指标，但通常所用的数学模型不足以研究国内市场指数运行规律。     

多元分布函数性质的若干注记

本文进一步讨论多元分布的连续性与它的边缘分布函数的连续性之间的关系，从而指出文献[2]与[5]中关于多元分布函数序列一致收敛性的两个定理之间的等价性，并且进一步改进多元分布序列一致收敛性的条件。     

Synthesis, Crystal Structure and Luminescence Property of [Co(hmz)_2(H_2O)_4]·2H_2O

A new mononuclear Co(II) complex, [Co(hmz)2(H2O)4]·2H2O, has been synthesized by the reaction of Co(CH3COO)2·4H2O with 1-(4-hydroxyphenyl)-5-mercaptotetrazole (Hhmz). It crystallizes in the monoclinic system, space group P21/n with a = 13.502(5), b = 6.718(3), c = 13.972(6) , β = 117.532(4)o, V = 1123.9(8) 3, Z = 2, M r = 553.45, F(000) = 570, Dc = 1.635 g/cm3, μ = 1.008 mm–1, the final R = 0.0272 and wR = 0.0684 for 2194 observed reflections (I > 2σ(I)). The Co(II) is six-coordinated by two nitrogen atoms from two hmz–1 ligands and four water molecules, forming an octahedral geometry. The intermolecular hydrogen bonding and offset-panel π-π stacking interactions between the adjacent molecules extend the compound into a three- dimensional supramolecular framework. The title compound emits strong blue fluorescent light (λem(max) = 427 nm) at room temperature and is red-shifted compared with free ligand Hhmz (λem(max) = 342 nm).     

Thrust generation and wake structure of wiggling hydrofoil

Marine animals and micro-machines often use wiggling motion to generate thrust. The wiggling motion can be modeled by a progressive wave where its wavelength describes the flexibility of wiggling animals. In the present study, an immersed boundary method is used to simulate the flows around the wiggling hydrofoil NACA 65-010 at low Reynolds numbers. One can find from the numerical simulations that the thrust generation is largely determined by the wavelength. The thrust coefficients decrease with the increasing wavelength while the propulsive efficiency reaches a maximum at a certain wavelength due to the viscous effects. The thrust generation is associated with two different flow patterns in the wake： the well-known reversed Karman vortex streets and the vortex dipoles. Both are jet-type flows where the thrust coefficients associated with the reversed Karman vortex streets are larger than the ones associated with the vortex diploes.     

多氨基多醚基亚甲基膦酸的合成及其阻垢机理的MD模拟

以端氨基聚醚、亚磷酸、甲醛、浓盐酸等为原料合成了新型水处理剂多氨基多醚基亚甲基膦酸(PAPEMP), 并通过红外、核磁等手段对产品进行了表征. 采用分子动力学(MD)模拟退火方法, 研究了周期性边界条件下PAPEMP与方解石晶体的相互作用, 探讨了该相互作用的本质, 并初步阐释了PAPEMP的阻垢机理. 结果发现, PAPEMP分子(n＝1～8)与方解石 晶面的结合能强弱排序依次为(按聚合度) 5＞6＞4＞3＞8＞2＞7＞1. 对体系各种相互作用以及对关联函数g(r)的分析表明, 超分子体系的结合能主要由库仑作用(包括离子键)提供, 并含少量氢键成分; van der Waals作用为正值, 不利于结合体系的形成. 能量分析表明, 与方解石晶面结合的PAPEMP (n＝1～8)分子均发生了明显的扭曲变形.     

Surface Morphology of GaAs/In0.3Ga0.7As in an Elastic Field of Static Point Defects

The surface morphology InGaAs layers with In composition of 0.3 on GaAs （001） substrates are simulated by the phase field method. We investigate the influence of the strain field induced by static point defects on surface morphology of the InGaAs thin film. Our simulation demonstrates that the rms roughness of the thin film surface is strongly dependent on the density and magnitude of the randomly distributed point defects. Point defects near the thin film surface can produce a relatively large change of the surface morphology. The influences of thin film thickness on the surface morphology with different defect distributions are illustrated in the simulations. Additionally, a combination of experiment and theory is used to examine the influence of the defect density and magnitude on the surface morphology and roughness.     

随机利率模型下养老基金的最优化管理

本讨论带有收益保障的养老计划在随机利率模型下的优化管理问题。通过分解养老基金，将有下限约束的退休收益优化问题转化为无约束的自融资基金优化问题，并在Vasicek利率模型下得到显示解。