EM-FEL边带不稳定性的单粒子理论分析

利用单粒子理论分析了主频电磁波为常振幅缓变相移的电磁波泵自由电子激光(EM-FEL)的边带不稳定性,导出了色散方程,进行了详细地分析与讨论,并求出在几种特殊情况下的不稳定性区域与最大线性增长率,由此得出一些重要的结论。     

Linear representation of M-estimates in linear models

Consider the linear regression model, y_i = x_iβ₀ + e_i, i = l,…,n, and an M-estimate β of β_o obtained by minimizing Σρ(y_i — x_iβ), where ρ is a convex function. Let S_n = ΣX_iX_iX_i and r_n = S_n^½ (β — β₀) — S_n ² Σx_ih(e_i), where, with a suitable choice of h(.), the expression Σ x_ix(e,) provides a linear representation of β. Bahadur (1966) obtained the order of r_n as n→ ∞ when β_o is a one-dimensional location parameter representing the median, and Babu (1989) proved a similar result for the general regression parameter estimated by the LAD (least absolute deviations) method. We obtain the stochastic order of r_n as n → ∞ for a general M-estimate as defined above, which agrees with the results of Bahadur and Babu in the special cases considered by them.     

A NEW APPROACH TO DISCRIMINATION AND CLASSIFICATION USING A HAUSDORFF TYPE DISTANCE

A new method of discrimination and classification based on a Hausdorff type distance is proposed. In two groups, the Hausdorff distance is defined as the sum of the furthest distance of the nearest elements of one set to another. This distance has some useful properties and is exploited in developing a discriminant criterion between individual objects belonging to two groups based on a finite number of classification variables. The discrimination criterion is generalized to more than two groups in a couple of ways. Several data sets are analysed and their classification accuracy is compared to that obtained from linear discriminant function and the results are encouraging. The method in simple, lends itself to parallel computation and imposes less stringent conditions on the data.     

Parametric relative survival regression using generalized linear models with application to Hodgkin's lymphoma

Changes in survival rates during 1940–1992 for patients with Hodgkin's disease are studied by using population-based data. The aim of the analysis is to identify when the breakthrough in clinical trials of chemotherapy treatments started to increase population survival rates, and to find how long it took for the increase to level off, indicating that the full population effect of the breakthrough had been realized. A Weibull relative survival model is used because the model parameters are easily interpretable when assessing the effect of advances in clinical trials. However, the methods apply to any relative survival model that falls within the generalized linear models framework. The model is fitted by using modifications of existing software (SAS, GLIM) and profile likelihood methods. The results are similar to those from a cause-specific analysis of the data by Feuer and co-workers. Survival started to improve around the time that a major chemotherapy breakthrough (nitrogen mustard, Oncovin, prednisone and procarbazine) was publicized in the mid 1960s but did not level off for 11 years. For the analysis of data where the cause of death is obtained from death certificates, the relative survival approach has the advantage of providing the necessary adjustment for expected mortality from causes other than the disease without requiring information on the causes of death.     

中国90后创业者社会特质与创业倾向关系研究

通过对中国大学生创业者、创业孵化器以及部分中国大学MBA与EMBA的90后创业者进行调研,建立多元线性回归模型,考察90后创业者的社会特质对创业倾向的影响。结果显示:创业者社会特质中创业自我效能感、创业激情、创业先前经验及创业能力均对创业倾向有正向影响,而创业警觉性与创业倾向与其没有显著关系。据此认为,90后创业者的创业能力在创业自我效能感、创业先前经验、创业激情对创业倾向的正向影响中有中介作用,在创业警觉性对创业倾向的影响中无中介作用。故应培养90后创业者创业自我效能感、创业警觉性、社会及行业等经验,营造良好社会环境与校园环境,提高环境对创业能力的针对性,使创业倾向增加并转化为创业实践。     

Small area estimation using reduced rank regression models

Abstract

Small area estimation techniques have got a lot of attention during the last decades due to their important applications in survey studies. Mixed linear models and reduced rank regression analysis are jointly used when considering small area estimation. Estimates of parameters are presented as well as prediction of random effects and unobserved area measurements.     

如何在经济管理中正确应用影子价格

根据线性规划有关理论,结合产品成本及利润的概念,讨论了影子价格在经济管 理中如何正确运用的问题,指出了这一领域存在的几个误区。借助企业产品的成本结构及定 价策略,进一步说明了影子价格的正确应用需要多学科的交叉配合。     

试析文学作品中语言前景化策略的动因

作为诗歌语言或者进一步说文学语言的标志性特征,前景化策略一直是文体研究中的一个重要课题。但在文献中该领域的研究大多为对前景化的效果和手段的分析,罕有对该策略应用动因的系统分析。然而,在读者解读文本的过程中,对作家应用前景化策略动因的解析无疑是非常重要的一环。为此,笔者在大量文献研究的基础上尝试性地提出了一个较为系统完整的分析模式:文学作品中前景化策略的运用是基于创造美学效果、引导读者对语篇的认知、构成前景化结构的衔接与连贯这三个基本目的,而作家采用前景化策略的深层动因是实现其交际意图,向读者传达其对自然、社会、人生的特定感悟。论文应用大量实例验证了该分析模式的可行性。     

基于H1总线的信息网络业务流分析

通过对基于H1总线的信息网络过程监控层的业务量测量与分析,证实了该业务量具有典型的统计自相似性.从理论上研究了多AR1序列累加生成自相似流的机理和多个自相似流的累加过程,给出了H1总线业务量自相似性产生的原因.结果表明,基于H1总线的信息网络过程监控层的网络流量服从统计自相似分布,是一种具有典型长相关性的网络流.     

迭代法迭代阵谱半径新上界

引用双严格对角占优的概念,针对线性方程组bAx=在求数值解时常用的迭代方法,给出了Jacobi和Gauss-Seidel迭代法迭代阵谱半径的新上界,该新上界优于严格对角占优矩阵条件下得到的已有的结果,是已有结果在更广泛矩阵类条件下的推广,对相应迭代法迭代阵谱半径的估计更加精确。最后给出了数值例子说明所给结果的优越性。