高速铁路对沿线城市可达性影响的实证分析

在对交通发展与沿线城市可达性关系研究的基础上,基于城市可达性的理论,以石武高铁为例,分别运用加权平均旅行时间和广义加权旅行时间这两种评价方法构建模型,对高铁开通前后沿线城市的可达性指标值进行估计,定量分析了石武高铁对其沿线10个城市可达性的影响,论证了高铁对其沿线城市可达性影响的机理。研究认为,加权平均旅行时间法只考虑高铁在缩短旅行时间方面的因素,得到的估计结果说明了石武高铁的开通显著提升了沿线城市可达性水平,提高幅度约为40%;而广义加权旅行时间法除了考虑旅行时间方面的因素外,还考虑到高铁票价的因素,得到的估计结果说明票价因素使石武高铁对沿线城市可达性水平影响的显著程度降低了,可行性提高幅度降至18%左右;高铁可以通过实行淡季或非高峰期票价折扣来提高客座率。     

Career trajectory in high school dropouts

This study considers the career trajectories of high school dropouts, which has been given little attention to in the literature. Considering worker heterogeneity for individuals who do not complete high school, we estimate possible career trajectories and investigate the traits related with the decision to drop out. Using latent class growth analysis, three kinds of career trajectories are identified: dead-end, stepping-stone, and advancing careers. Although the majority of dropouts are in the dead-end careers, about 30% are in the process of escaping low-status jobs through acquiring work experience. Individual traits, such as gender, race, and cognitive ability, as well as home computer access are significantly related to the different types of career trajectories.     

论汉魏诗歌在《沧浪诗话》评价体系中的地位

严羽《沧浪诗话》评论“以盛唐为法”,但我们并不能据此简单推定汉魏诗歌在严羽的评价中逊于盛唐。他在高度赞赏汉魏诗歌的艺术成就的同时,积极地寻求,并最终在盛唐诗歌中找到了自己的诗歌理想。汉魏诗歌在严羽的诗歌评价体系中．起着参照作用,即其作为高古真纯的诗歌类型,与盛唐诗歌做对比,并验证后者在内容与艺术结合方面相对更高的合理想度。     

以群众需求引导优质服务方向

计划生育技术服务工作开展多年,基本靠行政手段,强制措施。本文围绕计划生育技术服务工作,结合性病和艾滋病的预防、出生缺陷干预等来促进计划生育优质服务工作。     

A routine-based framework implementing workload control to address recurring disturbances

Abstract

This research focuses on responsiveness in high variety manufacturing environments. To achieve it, the article proposes to develop Dynamic Response Capabilities (DRCs) of the manufacturing system defined as the abilities to readjust the planned operating parameters of workload, capacity, and lead time, in the wake of disturbances. To inform their development, built on the Workload Control theory, a routine-based framework is proposed. The framework supports an integrated approach for the implementation of adaptive decision-making routines for workload, capacity, and lead time readjustments at different stages in the order fulfilment process. Findings from two empirical cases show the appropriateness of the framework to develop and utilise DRCs in different settings of disturbances. Results of a simulation study, with one of the case companies, also shows the effectiveness of the framework to drive performance improvements in presence of recurring disturbances leading to demand variability.     

基于随机化适应性Lasso的高维变量选择

Lasso等惩罚变量选择方法选入模型的变量数受到样本量限制。文献中已有研究变量系数显著性的方法舍弃了未选入模型的变量含有的信息。本文在变量数大于样本量即p>n的高维情况下,使用随机化bootstrap方法获得变量权重,在计算适应性Lasso时构建选择事件的条件分布并剔除系数不显著的变量,以得到最终估计结果。本文的创新点在于提出的方法突破了适应性Lasso可选变量数的限制,当观测数据含有大量干扰变量时能够有效地识别出真实变量与干扰变量。与现有的惩罚变量选择方法相比,多种情境下的模拟研究展示了所提方法在上述两个问题中的优越性。实证研究中对NCI-60癌症细胞系数据进行了分析,结果较以往文献有明显改善。     

高语境文化与低语境文化中的交际差异比较

语境,简言之就是语言赖以存在、被人们实际所使用的环境。美国人类学家霍尔（Hall）把语境分为高语境与低语境,并用高语境和低语境的不同来分析文化的多样性。在高语境文化与低语境文化中,语境和语言（编码信息）在意义传递上所起的作用是不相同的。高语境文化与低语境文化中的交际存在着明显的差异。     

Pitfalls in using Weibull tailed distributions

By assuming that the underlying distribution belongs to the domain of attraction of an extreme value distribution, one can extrapolate the data to a far tail region so that a rare event can be predicted. However, when the distribution is in the domain of attraction of a Gumbel distribution, the extrapolation is quite limited generally in comparison with a heavy tailed distribution. In view of this drawback, a Weibull tailed distribution has been studied recently. Some methods for choosing the sample fraction in estimating the Weibull tail coefficient and some bias reduction estimators have been proposed in the literature. In this paper, we show that the theoretical optimal sample fraction does not exist and a bias reduction estimator does not always produce a smaller mean squared error than a biased estimator. These are different from using a heavy tailed distribution. Further we propose a refined class of Weibull tailed distributions which are more useful in estimating high quantiles and extreme tail probabilities.     

面向中学的古典诗词教学设计

汉语言文学师范专业人才培养的目标,旨在培养基础教育领域从事语文教学的专业人员,因此课程设计应兼顾当前基础教育领域课程改革对教师在人文素养和职业技能等方面的要求。本文以古典诗词的教学为切入点,针对中学语文对古典诗词教学的要求,探讨大学阶段古典诗词的教学方法,力求在大学文学课程教学与中学语文教学之间形成有效的链接。     

价格促销对消费者品牌选择的影响研究

本文通过实验方法探索性地研究了价格促销对消费者品牌选择的非对称影响。研究表明:消费者对不同产品的价格敏感性有所不同;较贵重的笔记本电脑、手机等耐用消费品行业中的低端品牌在与高端品牌的短期价格竞争中会获得更多市场份额,而对较廉价的洗发水等非耐用消费品来说,高端品牌将会在降价促销时获益更多。本文研究结论与国外同类研究结论有所不同,对企业的定价决策有重要的理论指导意义。