具有内生性的随机变系数模型的PLS估计

在随机变系数模型中,自变量很可能与系数方程中的随机斜率相关,从而引起内生性问题.这样的内生性同样会导致标准的OLS (ordinary least squares)估计量有偏且非一致.本文通过非参方法来解决这种内生性问题.首先设定此种相关性为一个未知方程,将其直接加入模型,再利用PLS (profile least squares)方法进行估计.在给出确定性参数的渐近性质后,本文比较了PLS和OLS估计量的有限样本性质.Monte Carlo结果显示,一般而言,PLS方法都优于OLS方法.最后,本文以社会经济地位对学生成绩的影响为例,考察了PLS和OLS估计值的区别.     

通过随机排序的交替方向乘子法的矩阵恢复

为了解决交替方向乘子法（ADMM）在求解广义的鲁棒主成分分析（G-RPCA）模型时结果不收敛的问题,提出用随机排序的交替方向乘子法（RP-ADMM）来求解这一模型,并且通过数值模拟和实例验证证明了该算法的有效性。结果表明,该算法求解G-RPCA模型较目前已有的算法速度更快、鲁棒性更高;在处理同时被稀疏大噪声和稠密小噪声污染的图片时,能较理想地分离出图像的低秩部分、大噪声部分和小噪声部分。     

The modeling analysis of microwave emission from stratified media of non-uniform lunar cratered terrain surface for Chinese Chang-E 1 observation

In China’s first lunar exploration project,Chang-E 1,the multi-channel (3.0,7.8,19.35,37 GHz) microwave radiometers were aboard the satellite,with the purpose of measuring microwave brightness temperature from lunar surface and surveying the global distribution of lunar regolith layer thickness,and global evaluation of 3He content.To analyze the modeling of microwave radiative transfer from three-layered media of lunar surface,some factors,such as the cratered lunar surface roughness,scattering of regolith particulate medium with temperature profile,are discussed.Based on the statistics of the lunar cratered terrain and using Monte Carlo (MC) method,the cratered lunar surfaces are numerically generated.The triangulated network is utilized to divide the undulated lunar surface into discrete triangle meshes with the size 10 m as a digital surface topography.The reflectivities of each plane mesh are calculated,and the average reflectivity for all MC-realized lunar surfaces is obtained.It is found that under the spatial resolution of 30 km×30 km of Chang-E 1 radiometer observation,the lunar surface can be well modeled as a flat surface.It makes the predominance of the parameters,such as the regolith layer thickness and stratified structures,to be studied.Using the radiative transfer equation of stratified media with dense scatterers,the scattering coefficient of the regolith particulate medium is found negligible,and the emission is mainly governed by the absorptive property of the medium.Brightness temperature of multi-layered media,i.e.lunar soil,regolith layer with temperature profile and underlying rock media,are derived and calculated,and relevant main factors to affect the modeling and emission simulation are analyzed.     

RAPD analysis of genetic variability among Stylosanthes guianenesis accessions of resistant and susceptible to the stylo anthracnose

Stylosanthes guianenesis Sw. is an important tropical forage legume grown and utilized in the tropics and the subtropics of South China. Anthracnose, caused by Colletotrichum gloeosporioides (Penz.) Sacc., is a major constraint to the extensive use of Stylosanthes. Forty-five accessions of S. guianensis were assessed with RAPD for genetic diversity and for resistance to anthracnose. RAPD analysis was performed using twenty primers screened from 200 arbitrary oligonucleotides, and a 71.5% level of polymorphism was found. The dendrogram obtained with unweighted pair group method of averages (UPGMA) based on the RAPD data showed genetic similarity from 50% to 94% among all stylo accessions, and fourteen clusters were defined at 66.5% genetic similarity. Two strains of C. gloeosporioides from stylo in China were used for anthracnose resistance screening. All plant accessions showed variation in the reaction to two strains and the correlation of resistance had a value of 0.904. Multiple correspondence analysis displayed a random distribution of the resistance or susceptibility response with respect to the genetic diversity measured by RAPD analysis except one group. Mean distance was also calculated to determine the diversity within clusters. From our results, the RAPD analysis is an effective and efficient technique of providing quantitative estimates of genetic similarity among stylo accessions.     

多边形颗粒随机分布复合材料的模拟及其网格算法

针对颗粒为多边形且呈随机分布的多相复合材料,给出了计算机模拟．同时,对此二维区域提供了一个自动三角形网格剖分算法,通过程序实现,用实例说明了算法的有效性．此算法可推广到三维情形,如：裂纹材料等．     

巴氏空间的Burkholder不等式及应用

在一定的几何空间条件下,考虑B值鞅的Burkholder不等式及B值的Marcinkiewicz－Zygmund不等式的延伸,并且利用此结果讨论B值鞅的随机指标和的矩.     

用JavaScript实现远程教学中的动态交互功能

现代远程教育通常是采用B／S模式的教学网站，其中同用户动态交互功能部分，通常采用ASP或者其他动态网站建设技术．文章介绍一种基于JavaScript的静态页面处理技术，来实现远程教学中的动态交互功能．其中着重探讨了对数据库存取、动态随机组卷、以及阅卷评分功能的模拟实现．     

混合约束最优化问题的直接解法

针对可行域比较畸形的混合约束最优化问题 ,证明了联合应用消元法和随机方向搜索法求解该类问题的可行性 ,并给出了相应的算法和程序框图 .该算法具有良好的收敛性 ,但收敛速度将随着等式约束条件个数的增大而减小     

大鸨的随机扩增多态DNA分析与种内亲缘关系研究

利用随机扩增多态DNA技术对大鸨(Otis tarda)6个个体进行了随机扩增多态DNA分析,共筛选出有效随机引物14条,利用所得的随机引物对每只大鸨的基因组DNA进行扩增,共得到327个扩增片段,其中共有片段150个,根据聚类分析所得到的树状图确定了6只大鸨的亲缘关系.     

铜绿假单胞菌随机扩增DNA多态性基因分型研究

利用微量液体稀释法进行药敏检测和RAPD技术进行基因分型,调查了铜绿假单胞菌在临床各科中的流行情况,以期建立稳定的临床检测系统,在控制院内感染的流行病研究中发挥更大的作用.结果表明耐药谱分6型,Ⅰ型占44.5%,Ⅱ型占18.5%,Ⅲ型占7.4%,Ⅳ型占7.4%,Ⅴ型占11.1%,Ⅵ型(不定型)占11.1%;RAPD分9型,A型占51.9%,B型占7.4%,C型占7.4%,D型占7.4%,E型占7.4%,F型占3.7%,G型占3.7%,H型占7.4%,I型占3.7%.说明基因型A型、耐药谱Ⅰ型的铜绿假单胞菌是此次ICU医院感染暴发流行的菌株,其他型别为非流行相关菌株.比较结果还说明RAPD基因分型的灵敏性、特异性及可靠性优于耐药谱分型,在医院感染流行病学调查中具有较大的应用价值.