快速轨道交通对城市群可达性影响研究——以京津冀城市群为例

快速轨道交通是城市群主要城市间联系的骨架,是城市群一体化发展的重要基础。笔者通过对比分析国内外城市群的交通模式,建立可达性测度指标,分析快速轨道交通的发展对城市群内各城市可达性的影响,并以京津冀城市群为例,计算城市群可达性指标,基于快速轨道交通发展对城市群可达性的影响因素进行分析,以期为京津冀城市群快速轨道交通发展做出评估,为制定城市群轨道交通发展战略提供参考。     

The nested joint clustering via Dirichlet process mixture model

This article focuses on the clustering problem based on Dirichlet process (DP) mixtures. To model both time invariant and temporal patterns, different from other existing clustering methods, the proposed semi-parametric model is flexible in that both the common and unique patterns are taken into account simultaneously. Furthermore, by jointly clustering subjects and the associated variables, the intrinsic complex shared patterns among subjects and among variables are expected to be captured. The number of clusters and cluster assignments are directly inferred with the use of DP. Simulation studies illustrate the effectiveness of the proposed method. An application to wheal size data is discussed with an aim of identifying novel temporal patterns among allergens within subject clusters.     

工业取用水监测奇异数据挖掘与重构方法

提高工业取用水监测数据质量是目前国家水资源监控能力建设的重要内容,而奇异值问题已成为影响监测数据质量的关键短板。本文在解析现阶段工业取用水监测数据奇异值主要类型基础上,以国家水资源管理系统数据库中工业取用水监测数据为样本,利用小波变换模极大值模型提取工业取用水监测数据时频变化特征,并利用傅里叶函数对其残差序列进行修正,进而运用相对误差控制方法挖掘监测数据奇异值。在此基础上,采用混沌粒子群优化的最小二乘支持向量机模型重构填补奇异值数据。研究结果表明：小波变换模极大值模型能够较好地提取工业取用水监测数据序列的时频变化特征,但是同时容易导致监测数据的信息损失,利用傅里叶函数对小波变换进行残差修正则可进一步提升取用水监测数据序列的特征提取效果;以小波变换模极大值特征序列为基础,通过相对误差控制可实现对监测数据奇异值的高效挖掘;对于挖掘出的奇异值重构填补问题,可选取混沌粒子群优化的最小二乘支持向量机模型,其重构精度要优于多项式曲线拟合等传统统计学方法和普通最小二乘支持向量机模型。上述工业取用水监测数据奇异值挖掘重构策略为现阶段国家水资源监控能力建设的推进提供了重要技术方法支持。     

An omnibus two-sample test for ranked-set sampling data

We develop an omnibus two-sample test for ranked-set sampling (RSS) data. The test statistic is the conditional probability of seeing the observed sequence of ranks in the combined sample, given the observed sequences within the separate samples. We compare the test to existing tests under perfect rankings, finding that it can outperform existing tests in terms of power, particularly when the set size is large. The test does not maintain its level under imperfect rankings. However, one can create a permutation version of the test that is comparable in power to the basic test under perfect rankings and also maintains its level under imperfect rankings. Both tests extend naturally to judgment post-stratification, unbalanced RSS, and even RSS with multiple set sizes. Interestingly, the tests have no simple random sampling analog.     

China’s flexible overseas food strategy: food trade and agricultural investment between Southeast Asia and China in 1990–2015

Using the UN Comtrade database and multiple sources of agricultural investment data, this paper outlines the emerging patterns of food trade and agricultural investment between Southeast Asian countries and China. The paper shows that China has adopted a flexible overseas food strategy. First, China has increased food export and shifted its food trade with Southeast Asia from a dependent relationship towards a complementary relationship at the regional level in recent years. Second, China tends to adapt to the existing conditions of food production and trade in Southeast Asian countries instead of fundamentally altering them. Finally, Chinese overseas agricultural investment is less driven by domestic food demand but more oriented for profit making, and this gives it flexibility in diversifying investment. An adequate understanding of China’s flexible food strategy in bilateral and multilateral relationships holds implications for global food security.     

适度提高养老保险农民缴费档次的可行性分析

通过对不同经济发展程度地区农民参保情况的调查,发现目前农民在选择养老保险缴费时往往选择最低标准和档次的缴费。通过分析,认为城乡居民基本养老保险制度设计缺乏长远考虑、制度执行过程注重眼前利益、农民更倾向传统养老方式以及存在盲从心理等是城乡居民基本养老保险农民低档次缴费的原因。在对农民养老需求与缴费能力进行分析的基础上,认为当前可以适度提高农民缴费档次,通过采取更具有激励性的缴费政策、规范制度执行等措施来促进农民选择更高的缴费档次。     

产业集群持续竞争优势及其机理

基于资源和动态能力等企业战略管理视角,对产业集群持续竞争优势的构建进行分析,并建立相关概念模型,提出了本土组织机构、集体声誉、共享知识、竞合互动氛围等共享性资源本身及通过吸收能力和创新能力中介作用对集群持续竞争优势的影响机理,集体学习机制为资源的合理利用提供路径和渠道。     

农用地变更许可的法权表达

我国现行《土地管理法》第44条确立的农用地转用审批行为,是从程序层面严格执行土地用途管制的制度保障。变更农用地用途管制须遵守农用地转用审批程序,这由此确立了农用地用途变更许可制度。在法权逻辑层面,应将农用地用途变更许可行为归结为农用地开发许可法律制度的范畴。以农用地开发许可权的法律属性来定性农用地转用审批行为,可避免农用地转用审批这一事实行为游离于法律思维之外,而处于文本层面的灰色地带。     

Culturally responsive teaching in China: instructional strategy and teachers’ attitudes

The aim of this study was to investigate the manner in which teachers facilitate the pedagogical process within a culturally diverse student population. The study focused on two primary schools in China; one located in a more fully developed city in eastern China (Case A), while the other was in a less developed city in rural western China (Case B). This allowed the researchers to compare and analyse the different instructional practices by means of semi-structured interviews and questionnaires. The findings indicate that: the teachers in Case A demonstrated overall affirmative attitudes towards ethnic minority cultures, as well as towards the students belonging to those cultures. However, the teachers also chose not to mention the specific ethnic identities and cultural differences of the students during the course of their instruction in order to ensure equal treatment for everyone. This leads to a kind of ‘cultural blindness’ in the classroom. In Case B, opinions regarding minority cultures were more varied. Compared with the teachers in Case A, more teachers in Case B found minority cultures to be inferior to the dominant Han culture. Some teachers also, counter intuitively, were of the opinion that the minority cultures were even superior. At the instructional level, school leadership developed courses on local culture and ethnicity for the teaching staff. This was done for a variety of reasons. The strongest evidence to support culturally responsive teaching in Case A does not stem from teaching and learning demands but from the necessity to pursue characteristics that make them distinctive from other schools at the same time, Case B’s practice of culturally responsive teaching was strongly supported by the government and UNICEF. Teachers in both schools indicated that they had integrated their knowledge of ethnic minority groups into the subject matter when it was necessary.     

负面无用评论对消费者真的无用吗?

网络购物在线评论信息包含了大量看似无用的评论,该类评论对消费者产品购买态度是否会产生影响尚缺少相关研究。明晰负面无用评论对消费者购买意愿的影响机理对平台及企业有效管理用户在线评论具有一定的参考价值。本研究以无用评论信息作为研究对象,采用实验法,设置“负面无用评论”“负面有用评论”实验组以及“正面有用评论”对照组,解析负面无用评论对消费者购买意愿的影响及其内在机制,得到结论如下：在正面有用评论集中加入负面无用评论能提高消费者购买意愿,加入负面有用评论则会降低消费者购买意愿;负面评论展现出的无关内容越多,消费者感知到的风险越低,购买意愿越高;品牌熟悉度越高,消费者购买意愿受负面无用评论的影响越大。