Photopolymerizable Elastomers for Vascular Tissue Regeneration

The aim of this study was to design new resin formulations for blood vessel substitutes with small inner diameter that can be 3D-printed by Additive Manufacturing (AM). Commercially available urethane oligomer acrylates as crosslinking agents (CAs) with different reactive diluents (RDs) and/or thiol chain transfer agents (CTAs) were examined. It could be shown that the properties of photopolymers of carefully selected CA/RD/CTA combinations can be varied in a wide range, also to fit with those of natural blood vessels. Moreover, these materials showed good biocompatibility in in-vitro cell culture tests with endothelial cells. A new method to assess the tear resistance of the new materials in comparison with natural blood vessels was designed and established. The tear resistance of the developed photopolymers already approaches those of natural material, although there is still need of improvement. The 3D-structuring of optimized resin system succeeded. Hence AM has proven to be an ideal tool to manufacture parts with the complex structure of natural blood vessels.     

Two‐level additive Schwarz algorithms for nonlinear complementarity problem with an M‐function

Nonlinear complementarity problem (NCP) is a wide class of problems. In this paper, some two‐level additive Schwarz algorithms for NCPs with an M‐function are developed and analyzed. The algorithms are proved to be convergent monotonically and can reach the solution of the problem within finite steps. They may also offer a possibility of making use of fast nonlinear solvers for solving the subproblems involved in the algorithms. Some preliminary numerical results are reported. Copyright © 2009 John Wiley & Sons, Ltd.     

First passage of time-reversible spectrally negative Markov additive processes

We study the first passage process of a spectrally negative Markov additive process (MAP). The focus is on the background Markov chain at the times of the first passage. This process is a Markov chain itself with a transition rate matrix Λ. Assuming time reversibility, we show that all the eigenvalues of Λ are real, with algebraic and geometric multiplicities being the same, which allows us to identify the Jordan normal form of Λ. Furthermore, this fact simplifies the analysis of fluctuations of a MAP. We provide an illustrative example and show that our findings greatly reduce the computational efforts required to obtain Λ in the time-reversible case.     

具有核的态射广义Moore-Penrose逆

本文研究了具有核的态射广义Moore-Penrose逆.利用加边态射的可逆性,获得了态射广义Moore-Penrose逆存在的一些新的充要条件及相关表达式,推广了态射Moore-Penrose逆的相应结论.     

Singularities of the matrix exponent of a Markov additive process with one-sided jumps

We analyze the number of zeros of det(F(α))$det\left(F\left(\alpha \right)\right)$, where F(α)$F\left(\alpha \right)$ is the matrix exponent of a Markov Additive Process (MAP) with one-sided jumps. The focus is on the number of zeros in the right half of the complex plane, where F(α)$F\left(\alpha \right)$ is analytic. In addition, we also consider the case of a MAP killed at an independent exponential time. The corresponding zeros can be seen as the roots of a generalized Cramér–Lundberg equation. We argue that our results are particularly useful in fluctuation theory for MAPs, which leads to numerous applications in queueing theory and finance.     

次范整线性空间上的可加奇性算子

研究次范整线性空间上的可加奇性算子理论.引进可加奇性算子的三种不同的次范数和拟次范数,利用它们刻画可加奇性算子的三种有界性:有界、局部有界和球有界,深入讨论这三种有界性之间的关系,以及它们与连续性的关系.同时,还进一步研究次范整线性空间上连续可加奇性算子族的共鸣定理.     

ARMAX时间序列模型异常点及异常点斑片的估计和检测

将通常的Gibbs抽样和自适应的Gibbs抽样算法用于带有外生变量的自回归移动平均时间序列(ARMAX)模型的Bayes分析,首先采用一些方法消除ARMAX模型中输入(外生变量)序列的影响,然后在前人工作的基础上给出了一种类似的挖掘相应时间序列中的异常点及异常点斑片的方法.说明了自适应的Gibbs抽样算法也能够有效地检测ARMAX模型中孤立的附加型异常点及异常点斑片.实际的和模拟的结果也显示这些方法可以明显减少掩盖和淹没现象的发生,这是对已有工作的推广和扩充.     

风险资产市场组合的概率分布和均值估计

探讨CAPM中风险资产市场组合的概率分布和均值估计问题.在股票价格行为模型用维纳过程(又称布朗运动)表述的前提下,证明了CAPM中的市场组合服从加法逻辑正态分布的结论,进而给出了市场组合均值的3种估计.以此为基础进行CAPM的实证检验,才具有理论上的严密性.     

交叉关联噪声对光学双稳系统平均首通时间的影响

研究了乘性色噪声和加性白噪声驱动的光学双稳系统中噪声对系统两个方向平均首通时间T₊（x_s1→x_s2）和T_-（x_s2→x_s1）的影响（平均首通时间是指从一稳态出发越过势垒到另一稳态所用时间的平均值）.通过Novikov定理和Fox近似方法得到相应的Fokker-Planck方程,利用最速下降法得到T₊（x_s1→x_s2）和T_-（x_s2→x_s1）的表达式.研究发现：乘性噪声强度Q和加性噪声强度D对T₊（x_s1→x_s2）的影响相同,对T_-（x_s2→x_s1）的影响不同;T₊（x_s1→x_s2）随乘性色噪声自关联时间τ的增大而增大,但随噪声间的交叉关联强度λ的增大而减小;T_-（x_s2→x_s1）随τ的增大而减小,随λ的增大而增大. 关键词： 平均首通时间 光学双稳系统 乘性色噪声 加性白噪声     

Structure and mechanical properties of Ni-P electrodeposited coatings

The coatings with different phosphorus contents were obtained by varying the concentration of H₃PO₃ in the electroplating bath. With the increase of phosphorus content, the structure of the Ni-P electrodeposited coatings transformed from microcrystalline to a mixture of nanocrystalline and amorphous phases, then to amorphous phase. A high hardness value of 710 HV_0.1 of as-deposited Ni-P coating was obtained at 8.3 at.% phosphorus content, and high wear resistance was accordingly achieved. The refined nanocrystalline grains with average size of about 7 nm were found to be responsible for the high hardness and improved wear resistance of the as-deposited Ni-P electrodeposited coating.