基于ANSYS的三维动态建模系统研究与开发

针对ANSYS软件三维数值建模的复杂性,基于三次样条插值法和趋势面分析原理,采用Borland Delphi 6.0可视化程序设计语言开发出了三维动态自动建模系统。该系统具有操作性好、建模准确等优点,提高了建模效率,便于多方案的模拟计算。     

关于科技文献老化B-K方程的多项式回归分析

本文用多项式回归分析理论检验了文献老化B－K方程，验证了B－K方程中系数的特征。     

Distribution of C4 plants along the Northeast China transect and its correlation to the environmental factors

The distribution of C₄ plants and the C₄/C₃ ratio along Northeast China transect (NECT) have been studied. A model to quantify their relation with environmental factors has been set up. The ratio of the number of C₄ plants to that of C₃ plants along NECT shows two low and two high trends from east to west, and their distribution is mainly decided by annual average temperature and precipitation.     

女性全血比粘度参考值与地理因素回归分析

为制定中国健康女性全血比粘度参考值的一标准提供科学依据，收集了中国各地用毛细管法测定的健康女性全血比粘度参考值，对其与地理因素的关系进行了研究，发现海拔高度是影响健康女性全血比粘度参考值最主要的因素，随着海拔高度的逐渐增大，健康女性全血比粘度参考值也在逐渐增大，相关性显著，用多元回归分析的方法推导出了一回归方程，如果知道了中国某地的地理因素，就可用回归方程估算这个地区的健康女性全血比粘度参考值。依     

Application of NIR spectroscopy for firmness evaluation of peaches

The use of near infrared （NIR） spectroscopy was proved to be a useful tool for quality analysis of fruits. A bifurcated fiber type NIR spectrometer, with a detection range of 800-2500 nm by InGaAs detector, was used to evaluate the firmness of peaches. Anisotropy of NIR spectra and firmness of peaches in relation to detecting positions of different parts （including three latitudes and three longitudes） were investigated. Both spectra absorbency and firmness of peach were influenced by longitudes （i, ii, iii） and latitudes （A, B, C）. For modeling, two thirds of the samples were used as the calibration set and the remaining one third were used as the validation or prediction set. Partial least square regression （PLSR） models for different longitude and latitude spectra and for the whole fruit show that collecting several NIR spectra from different longitudes and latitudes of a fruit for NIR calibration modeling can improve the modeling performance. In addition, proper spectra pretreatments like scattering correction or derivative also can enhance the modeling performance. The best results obtained in this study were from the holistic model with multiplicative scattering correction （MSC） pretreatment, with correlation coefficient of cross-validation γcv=0.864, root mean square error of cross-validation RMSECV=6.71 N, correlation coefficient of calibration r=0.948, root mean square error of calibration RMSEC=4.21 N and root mean square error of prediction RMSEP=5.42 N. The results of this study are useful for further research and application that when applying NIR spectroscopy for objectives with anisotropic differences, spectra and quality indices are necessarily measured from several parts of each object to improve the modeling performance.     

用带参数的三次样条插值方法解两点边值问题

用带参数的三次样条插值方法计算一类两点边值问题的近似解,证明这类方法对于任意的参数τ都是二阶收敛的.最后用数值例子验证这种方法.     

不同被解释变量选择对决定系数R2的影响研究

考虑了一元线性回归模型中不同被解释变量选择对决定系数的影响，在一定条件下，证明了不同被解释变量回归模型的决定系数存在特定关系。     

Urban structure and the risk of influenza A （H1N1） outbreaks in municipal districts

Changsha was one of the most affected areas during the 2009 A （H 1N 1） influenza pandemic in China. Here, we analyze the spatial-temporal dynamics of the 2009 pan- demic across Changsha municipal districts, evaluate the relationship between case incidence and the local urban spatial structure and predict high-risk areas of influenza A （H1NI）. We obtained epidemiological data on all cases of influenza A （H1NI） reported across municipal districts in Changsha dur- ing period May 2009-December 2010 and data on population density and basic geographic characteristics for 239 primary schools, 97 middle schools, 347 universities, 96 mails and markets, 674 business districts and 121 hospitals. Spatial- temporal K functions, proximity models and logistic regres- sion were used to analyze the spatial distribution pattern of influenza A （H1N1） incidence and the association between influenza A （HINI） cases and spatial risk factors and predict the infection risks. We found that the 2009 influenza A （H 1N 1 ） was driven by a transmission wave from the center of the study area to surrounding areas and reported cases increased significantly after September 2009. We also found that the distribution of influenza A （H 1N1） cases was associ- ated with population density and the presence of nearest public places, especially universities （OR = 10.166）. The final pre- dictive risk map based on the multivariate logistic analysis showed high-risk areas concentrated in the center areas of the study area associated with high population density. Our find- ings support the identification of spatial risk factors and high- risk areas to guide the prioritization of preventive and miti- gation efforts against future influenza pandemics.     

截断非平衡似无关模型的极大仿真似然估计

样本数据缺失和截断是现代统计调查中经常遇到的两个问题，它们在一定程度上影响模型参数估计的准确性和有效性. 该研究首先提出了一个新的截断非平衡似无关回归模型，这个模型能够同时考虑数据缺失和截断的特征；然后基于Geweke-Hajivassiliou-Keane（GHK）的仿真算子，建立了该模型的极大仿真似然估计方法；蒙特卡罗实验结果表明，在大样本和有限样本下这种估计方法在参数估计的准确性和有效性方面均具有良好表现.