琥乙红霉素分子印迹聚合物微球的制备及表征

以琥乙红霉素为模板分子,甲基丙烯酸为功能单体,乙二醇二甲基丙烯酸酯为交联剂,采用悬浮聚合法制备得到了平均粒径约为60μm的琥乙红霉素分子印迹聚合物微球(MIPs),并用扫描电镜对其表面形貌进行了表征。考察了琥乙红霉素分子印迹聚合物的印迹效果,研究了琥乙红霉素分子印迹聚合物的动力学吸附特性。比较了MIPs对琥乙红霉素及其它3种抗生素的吸附情况。结果表明,制备得到的琥乙红霉素分子印迹聚合物微球对琥乙红霉素具有最好的吸附能力,显示出MIPs具有高的选择性。     

柔性壁面湍流边界层相干结构控制的实验研究

本文利用热膜测速技术对刚性壁面和柔性壁面湍流边界层的流向速度分量进行了实验测量,首先研究了柔性壁面对平均速度分布和湍流度分布的影响,结果表明:柔性壁面的边界层速度分布在对数律层向上有所平移,缓冲层加厚,具有一般的壁面减阻特征;而柔性壁的湍流度比刚性壁的湍流度要低,分布也更为平坦。然后综合运用自相关法和条件采样技术研究了湍流近壁区的相干结构,结果表明:刚性壁自相关曲线的第二峰值出现的时间比柔性壁的短,柔性壁的猝发频率比刚性壁的低许多。实验结果表明柔性壁面具有一定的减阻作用。     

悬索桥的非线性分析

为进行悬索桥的几何非线性分析，建立了梁单元的刚度矩阵及有关算法，通过算例验证了方法是可行的。     

广义变系数模型的Bayesian B样条估计

提出了广义变系数模型函数系数的一种新的估计方法．我们用B样条函数逼近函数系数,不具体选择节点的个数,而是节点个数取均匀的无信息先验,样条函数系数取正态先验,用Bayesian模型平均的方法估计各个函数系数．这种估计方法一个主要特点是允许各个函数系数所需节点个数的后验分布不同,因此允许不同函数系数使用不同的光滑参数．另外,本文还给出了Bayesian B样条估计的计算方法,并通过模拟例子,说明广义变系数模型的函数系数可以由Bayesian B样条估计方法得到很好的估计．     

Automated rejection sampling from product of distributions

Summary  Sampling from probability density functions (pdfs) has become more and more important in many areas of applied science, and has therefore been the subject of great attention. Many sampling procedures proposed allow for approximate or asymptotic sampling. On the other hand, very few methods allow for exact sampling. Direct sampling of standard pdfs is feasible, but sampling of much more complicated pdfs is often required. Rejection sampling allows to exactly sample from univariate pdfs, but has the huge drawback of needing a case-by-case calculation of a comparison function that often reveals as a tremendous chore, whose results dramatically affect the efficiency of the sampling procedure. In this paper, we restrict ourselves to a pdf that is proportional to a product of standard distributions. From there, we show that an automated selection of both the comparison function and the upper bound is possible. Moreover, this choice is performed in order to optimize the sampling efficiency among a range of potential solutions. Finally, the method is illustrated on a few examples.     

超总体模型下有限总体的估计

超总体模型是抽样理论与统计学其它分支联系的桥梁,借助于超总体模型研究抽样理论是一个有前途的方法．本文综述了这方面的结果,包括总体目标量的估计及其精度估计,同时提出了若干未来的研究问题．     

基于均匀设计抽样遗传算法求解背包问题

众所周知,遗传算法的运行机理及特点是具有定向制导的随机搜索技术,其定向制导的原则是:导向以高适应度模式为祖先的"家族"方向.以此结论为基础,利用均匀设计抽样的理论和方法,对遗传算法中的交叉操作进行了重新设计,给出了一个新的GA算法,称之为均匀设计抽样遗传算法.最后将均匀设计抽样遗传算法应用于求解背包问题,并与简单遗传算...     

Speeding up the FMMR perfect sampling algorithm: A case study revisited

In a previous paper by the second author, two Markov chain Monte Carlo perfect sampling algorithms—one called coupling from the past (CFTP) and the other (FMMR) based on rejection sampling—are compared using as a case study the move‐to‐front (MTF) self‐organizing list chain. Here we revisit that case study and, in particular, exploit the dependence of FMMR on the user‐chosen initial state. We give a stochastic monotonicity result for the running time of FMMR applied to MTF and thus identify the initial state that gives the stochastically smallest running time; by contrast, the initial state used in the previous study gives the stochastically largest running time. By changing from worst choice to best choice of initial state we achieve remarkable speedup of FMMR for MTF; for example, we reduce the running time (as measured in Markov chain steps) from exponential in the length n of the list nearly down to n when the items in the list are requested according to a geometric distribution. For this same example, the running time for CFTP grows exponentially in n. © 2003 Wiley Periodicals, Inc. Random Struct. Alg., 2003     

Numerical Study of φ4 Model by Potential Importance Sampling Method

We investigate the phenomena of spontaneous symmetry breaking for φ⁴ model on a square lattice in the parameter space by using the potential importance sampling method, which was proposed by Milchev, Heermann, and Binder [J. Stat. Phys. 44 (1986) 749]. The critical values of the parameters allow us to determine the phase diagram of the model. At the same time, some relevant quantities such as susceptibility and specific heat are also obtained.     

非均匀采样干涉数据光谱反演技术研究

干涉光谱成像仪获取的干涉数据是一种中间数据,需要进行光谱反演才能够得到目标光谱数据,傅里叶变换方法是常规的光谱反演方法。由于干涉数据中存在非均匀采样问题,若忽略光谱混叠,直接采用快速傅里叶变换会导致反演光谱的失真,难以满足实时处理需求。针对非均匀采样干涉数据的光谱反演需求,将插值及非均匀快速傅里叶变换(NUFFT)方法应用到光谱反演处理中,对过采样及部分欠采样情况下的非均匀采样干涉数据,提出了相应的光谱反演方法,并分析了方法的适用性。最后对过采样及部分欠采样情况下的光谱反演方法进行计算机仿真,过采样情况下采用NUFFT方法反演光谱的精度要明显高于插值方法,而部分欠采样情况下插值方法反演光谱的精度要明显高于NUFFT方法,并对欠采样造成的光谱混叠有一定的修正,验证了方法的有效性。