螺杆截面形状的数值拟合方法研究

研究了曲线拟合方法的特点,讨论了三次样条曲线和参数三次样条曲线的拟合方法在螺杆截面廓形拟合中的应用,给出了拟合的方程,并用实例验证了拟合的效果.同时解决了拟合过程中的单调性、失真、端点切向量的确定方法等一些关键技术问题.该方法为精确地生成刀具轨迹提供了光滑的型线方程.     

论房地产价格的理性回归

从目前来看,在国家近期一系列针对房地产市场调控政策密集出炉的情况下,房地产市场必将迎来极为关键的一年,预计全年仍将保持平稳运行态势,但投资、销售增速将有所放缓。住房直接关系到人民群众的日常生活,遏制房价过快上涨有利于房地产市场平稳健康发展,有利于满足老百姓不断增长的物质需求,有利于推动经济平稳较快发展,有利于促进社会和谐与稳定。所以,遏制房价过快上涨,引导房地产价格理性回归,于国于民有利。     

C^2连续的有理三次Bézier样条插值曲线

有理Bézier曲线具有很多良好的性质,是曲线曲面设计的重要方法.根据给定的型值点,通过构造有理Bézier样条插值曲线的公式,给出了计算方法,并且分析了重节点情形曲线的形状和特点,最后通过数值实例验证了方法的有效性.     

部分线性模型的光滑样条推断

运用光滑样条估计部分线性模型中的非参数函数,利用限制最大似然或广义交叉验证(GCV)的方法选择光滑参数,主要考察了部分线性模型的光滑样条估计以及有关非参数函数部分的假设检验.基于光滑参数的选择方法,提出了部分线性模型中的非参数函数是否为多项式函数的假设检验方法,并通过模拟例子研究本文提出的推断效果.     

我国女子田径前八名成绩发展趋势剖析

运用文献资料法、数理统计法、数学与灰色预测分析法以及相关SPSS、EXCEL和MATLAB建模软件等,对27届、28届和29届奥运会（2000—2008年）我国女子田径项目各单项奥运会最好成绩进行统计、分析与研究,以期了解八年来中国女子田径项目各单项的发展态势。     

长三角区域轻纺行业知识溢出效应分析

根据长三角地区轻纺行业的基本特征和知识来源,由全要素生产率函数建立知识溢出密度系数模型,通过实测数据回归拟合,判断出行业间的Jacob形式知识溢出效应比行业内的更为显著;进一步,基于劳动生产率建立企业内部微观环境下知识溢出贡献率模型,结果显示,熟练劳动力对非熟练劳动力有一定的知识溢出效应,但劳动力之间的血缘亲团关系对生产效率并无显著正向影响。     

基于逐步回归分析的上海会展业竞争力评价研究

上海的会展业持续发展。经济环境竞争力和旅游产业环境竞争力两个方面的因素影响了会展业竞争力。超大城市的会展业发展更取决于城市整体经济发展,而与旅游业相关较小。上海应继续发挥和强化经济环境竞争力优势;积极开拓外资渠道和形式;增强会展业与旅游业之间协调性;利用创新思想发展酒店业。     

Relevance of student and contextual school variables in explaining a student’s severity of violence experienced

Teachers conceptualise and interpret violent behaviour of secondary students in different ways. They also differ in their estimates of the relevance of student and contextual school variables when explaining the severity of violence experienced by students. Research can assist here by explicating the role of different types of contextual school variables. The research question is twofold: (1) Do contextual school variables, in addition to a student’s personal, family and educational variables, explain a student’s violent behaviour? (2) If so, what is the role of student composition variables compared with variables indicating the social cohesion of the school? A hypothetical model was developed in which personal, family, educational and school variables of different types simultaneously explain the severity of violence experienced by a student. The method used to test the model empirically is secondary analysis of data collected in a Dutch national survey on school safety in secondary education (N students = 78,840; N schools = 219). Severity of violence experienced is assessed by the Mokken Scale on Severity of Violence Experienced (MSSVE). Multiple regression analyses reveal that a student who is older, a young male, born in the country of residence, feels at home in another country, does not have an intact family, is not religious, is enrolled in the highest educational track and is achieving lower marks in the school subjects of language and mathematics, experiences more severe violence than other students (explained variance 3.4%). Simultaneously, different types of contextual school variables are differently relevant. Mean severity of violence experienced by students at school indicates clearly more variance (2.3%) than the combination of student composition variables (.4%). The conclusion is that the theoretical model is empirically supported, which also underlines the validity of the MSSVE. The discussion focuses on a comprehensive multilevel approach to stimulate and check improvement of social cohesion at school.     

Instrumental Variables Two-Stage Least Squares (2SLS) vs. Maximum Likelihood Structural Equation Modeling of Causal Effects in Linear Regression Models

In the presence of omitted variables or similar validity threats, regression estimates are biased. Unbiased estimates (the causal effects) can be obtained in large samples by fitting instead the Instrumental Variables Regression (IVR) model. The IVR model can be estimated using structural equation modeling (SEM) software or using Econometric estimators such as two-stage least squares (2SLS). We describe 2SLS using SEM terminology, and report a simulation study in which we generated data according to a regression model in the presence of omitted variables and fitted (a) a regression model using ordinary least squares, (b) an IVR model using maximum likelihood (ML) as implemented in SEM software, and (c) an IVR model using 2SLS. Coverage rates of the causal effect using regression methods are always unacceptably low (often 0). When using the IVR model, accurate coverage is obtained across all conditions when N = 500. Even when the IVR model is misspecified, better coverage than regression is generally obtained. Differences between 2SLS and ML are small and favor 2SLS in small samples (N ≤ 100).     

基于教育经费的人均可支配收入分析与预测

选取1992-2010年全国教育经费数据和2001-2011年城镇居民人均可支配收入数据,通过计量经济学分析建立两者动态回归模型,以此探究国家教育经费对人均可支配收入的影响。运用实证分析对人均可支配收入走势进行预测,得到了关于人均可支配收入波动趋势、周期、异动的相关结论。人均可支配收入在“十二五”期间仍将保持上涨趋势,其增长率波动周期大致为5年。