改进PCA方法的牙颌特征提取和数据集构建

为了提高牙颌数字模型特征提取的准确性和牙齿分割的效率,提出一种几何变换和主成分分析相结合的坐标系标准化方法,并以离散曲率、法向量、形状直径函数和离散测地距离为基础特征对牙颌数字模型进行了特征提取,在此基础上进一步扩展构建了76个特征数据集。采用提出的坐标系标准化方法和数据集对上颌进行了牙齿分割实验。结果表明：改进主成分分析方法能够快速准确地实现牙颌数字模型坐标系对齐,能够准确识别牙齿的特征信息并作出标记,牙齿分割完整,平均分割准确率达到99.74%。基于改进主成分分析方法的牙颌模型特征提取方法能够极大地提高特征对牙齿的区分性,从而降低位姿对牙颌特征提取带来的负面影响,实现在特征数据较少的情况下准确分割牙齿,可为数字化口腔诊疗提供一定的参考。     

高职院校应用英语专业课程体系改革初探

高职教育能够可持续地科学发展的关键在于高职教育事业软件的建设,其核心就是要尽快建立起“以就业为导向,以技术应用”为主线,以“零距离”上岗为目标的符合高职教育规律的课程体系.我国在这方面的研究还处于探索阶段,本文尝试提出符合高职教育发展方向课程体系的设计程序及以技术应用为主线的课程体系,以新的视角和务实的态度探讨这一核心问题,以望对高职教育的发展有所贡献.     

测距仪距离改正数的显著性检验及其检定精度

本文讨论了测距仪的加常数a、乘常数b和距离改正数ΔS(=a+bS)的显著性检验问题。讨论的结果表明,加常数和乘常数的显著性并不能决定距离改正数的显著性。所以,我们应当对距离改正数进行显著性检验,以决定是否用它来对观测边长进行改正。本文还从公式论证和模拟试验两个方面讨论了距离改正数的检定精度及其可靠性问题。     

Social distance between workers: An application to Italian geographic areas

This paper is concerned with the measurement of social distance, clustering, or polarization between workers of a given society. This concept is fundamentally different from that of inequality and thus cannot be measured by any Lorenz consistent index. Similarly, it cannot be additively decomposed into within - and between -group components using classical techniques. A new decomposition method is proposed and applied to Italian workers. The method provides an index that can be used both to calculate the distance between social groups classified according to worker characteristic and to track changes across time. The new method also reveals the factors that are reshaping the wage distribution and allows us to identify precisely where these effects are having their greatest impact.
JEL classification: D30, D63, I32.     

不同距离下灰函数极限的一致性

本文讨论了不同距离下灰函数权限的一致性,并给出不同距离下的极限转化定理。     

远程教育和大学图书馆

综述了我国远程教育的发展及我国大学图书馆网络化建设的状况 ,并在借鉴美国大学图书馆为远程教育服务的经验的基础上 ,从 4个方面探讨了我国大学图书馆为远程教育服务的发展方向 :1 )与提供远程教育的网站合作 ;2 )设立与远程教育相适应的专门机构 ;3 )提供远程教育的辅助教学 ;4)重视网上信息资源建设。     

Multiple Comparisons with the Best: Bayesian Precision Measures of Efficiency Rankings

A large literature measures the allocative and technical efficiency of a set of firms using econometric techniques to estimate stochastic production frontiers or distance functions. Typically, researchers compute only the precision of individual efficiency rankings. Recently, Horrace and Schmidt (Journal of Applied Economics 15, 1–26, 2000) have applied sampling theoretic statistical techniques known as multiple comparisons with a control (MCC) and multiple comparisons with the best (MCB) to make statistical comparisons of efficiency rankings. As an alternative, this paper offers a Bayesian multiple comparison procedure that we argue is simpler to implement, gives the researcher increased flexibility over the type of comparison, and provides greater, and more intuitive, information content. For these methods and a parametric bootstrap technique, we carry out multiple comparisons of technical efficiency rankings for a set of U.S. electric generating firms, estimated using a distance function framework. We find that the Bayesian method provides substantially more precise inferences than obtained using the MCB and MCC methods.Jel Classification: C11, C32, D24.     

Nonparametric density estimates consistent of the order of <Emphasis Type="Italic">n</Emphasis><Superscript>−1/2</Superscript> in the <Emphasis Type="Italic">L</Emphasis><Subscript>1</Subscript>–norm

We introduce an approximate minimum Kolmogorov distance density estimate of a probability density f₀ on the real line and study its rate of consistency for n. We define a degree of variations of a nonparametric family of densities containing the unknown f₀. If this degree is finite then the approximate minimum Kolmogorov distance estimate is consistent of the order of n^–1/2 in the L₁-norm and also in the expected L₁-norm. Comparisons with two other criteria leading to the same order of consistency are given.Received June 2002     

Cultural distance,investment flow,and control in cross‐border cooperation

Previous research analyzing the impact of cultural distance on joint venture negotiations has often confounded firm and environment effects. To decouple these effects, the cross‐border cooperation preferences of small and medium‐sized Korean firms were studied, considering simultaneously firms involved in inward and outward investment ventures. While cultural distance showed no significant relationship with the degree of control sought over the cooperative ventures, cultural distance was significantly related with a preference for ventures in domestic or foreign markets. The impact of cultural distance was found to be greater in inward investment than in outward investment. Copyright © 2008 John Wiley & Sons, Ltd.     

资源环境约束下中国经济效率的区域差异及动态演进

在保持经济高速增长同时,节约资源、保护环境,已成为我国可持续发展所面临的迫切问题。本文利用1989～2009年省际投入产出数据,分析研究资源环境约束下中国经济整体增长绩效的区域差异及动态演化过程。研究发现:(1)1989～2009年间我国整体环境无效率值为0.1684,能源消耗和污染排放所产生的无效率值合计为0.1251,约占到环境无效率总量的74.3%,是导致环境无效率的主要来源;(2)在分析期间我国环境无效率呈现出中间低、两端高的特点,2004年之后与污染排放相关的无效率值出现了大幅度反弹,是导致近期环境技术效率下降的主要原因;(3)区域间经济环境技术效率存在较大差异,东部沿海地区经济发展与环境关系较为和谐,但中西部地区环境技术效率普遍较低,且中部和西部的差异主要体现在经济增长层面;(4)在分析期间中国不同地区环境技术效率呈现出从发散到收敛的特征,主要与东部和中部环境技术效率近期的下降有关。最后,本文结合分析结果对中国经济发展方式转变提供了相关建议。