基于LDA主题模型的自贸区治理政策文本聚类分析——以辽宁自贸区为例

聚焦不同时期辽宁自贸区发展建设的政策,通过LDA大数据模型对自贸区建设的阶段性政策文本进行低维主题集合,能够识别大规模文档集中潜藏的主题信息、主题强度及结构特征。在此基础上,对比中央对辽宁自贸区的发展要求,能够准确发掘地方政策实施的侧重点与发展差距,进而识别自贸区建设发展的不足。研究发现：在主题强度上,主题间相似度较低且强度差距不明显;在主题领域上,政策颁布更侧重于行政审批、监管创新、项目建设等领域,而在投资、贸易、外汇管理、金融服务、科技创新、人才政策等领域较薄弱;在主题结构上,行政审批、绩效考核政策主题针对行政体制机制改革,监管创新、政府信息公开、电子信息化服务主题体现“服务型政府”的政策供给重点。基于此,需加强金融贸易、法治营商环境建设、人才引进、企业扶持等领域的政策供给。LDA主题模型;辽宁自贸区;政策文本;聚类分析     

Modified linear discriminant analysis using block covariance matrix in high-dimensional data

Among many classification methods, linear discriminant analysis (LDA) is a favored tool due to its simplicity, robustness, and predictive accuracy but when the number of genes is larger than the number of observations, it cannot be applied directly because the within-class covariance matrix is singular. Also, diagonal LDA (DLDA) is a simpler model compared to LDA and has better performance in some cases. However, in reality, DLDA requires a strong assumption based on mutual independence. In this article, we propose the modified LDA (MLDA). MLDA is based on independence, but uses the information that has an effect on classification performance with the dependence structure. We suggest two approaches. One is the case of using gene rank. The other involves no use of gene rank. We found that MLDA has better performance than LDA, DLDA, or K-nearest neighborhood and is comparable with support vector machines in real data analysis and the simulation study.     

LD侧泵浦固体激光器的热效应分析和模拟研究

针对大功率二极管阵列侧泵浦固体激光器产生的热效应进行了分析;同时根据所建立的理论模型,利用计算机模拟了不同泵浦强度、不同泵浦结构和不同边界冷却条件下,固体工作物质内热透镜焦距的变化和热致退偏强度的分布,并在此基础上提出了补偿热效应的具体措施     

Novel concentration-QTc models for early clinical studies with parallel placebo controls: A simulation study

The QTc interval of the electrocardiogram is a pharmacodynamic biomarker for drug-induced cardiac toxicity. The ICH E14 guideline Questions and Answers offer a solution for evaluating a concentration-QTc relationship in early clinical studies as an alternative to conducting a thorough QT/QTc study. We focused on covariance structures of QTc intervals on the baseline day and dosing day (two-day covariance structure,) and proposed a two-day QTc model to analyze a concentration-QTc relationship for placebo-controlled parallel phase 1 single ascending dose studies. The proposed two-day QTc model is based on a constrained longitudinal data analysis model and a mixed effects model, thus allowing various variance components to capture the two-day covariance structure. We also propose a one-day QTc model for the situation where no baseline day or only a pre-dose baseline is available and models for multiple ascending dose studies where concentration and QTc intervals are available over multiple days. A simulation study shows that the proposed models control the false negative rate for positive drugs and have both higher accuracy and power for negative drugs than existing models in a variety of settings for the two-day covariance structure. The proposed models will promote early and accurate evaluation of the cardiac safety of new drugs.     

基于消费者在线评论数据的快递物流服务质量评价研究

挖掘、明晰及满足消费者需求,是影响与提升快递物流服务质量的关键因素。以菜鸟平台在线评论的文本数据为爬虫数据源,针对所获取的6.5万条数据,运用TF-IDF算法、词云图、语义网络关联分析、LDA主题模型等文本量化分析,构建情感词典并进行文本情感赋值与分析。研究发现：时效性、价格合理性、服务优质性、应用平台功能性是消费者对快递物流服务质量产生消极情感倾向的关键因素。为提升消费者对快递物流服务质量的评价,需从提升物流供应链的时效性、完善物流价格制度的合理性、提高物流服务的优质性、优化物流应用平台的功能性方面予以重视。     

双十一活动消费者满意度研究——基于天猫个护美妆类产品文本挖掘

以2021年10月15日至11月30日天猫商城个护美妆的消费者评论数据为样本,运用文本挖掘的方式研究“双十一”活动及活动前后的消费者满意度,并对比2020年同时期,研究“双十一”满意度的演变可得出三个结论：(1)2021年“双十一”满意度评分为0.699 1,满意度相对较高,2021年“双十一”满意度的影响因素有：产品本身、“双十一”优惠活动、物流系统、虚假活动、售后服务;(2)2021年“双十一”活动满意度低于同年“双十一”之前,并在“双十一”之后持续下降,影响满意度前后变动的因素有：“双十一”优惠活动的落差、客服人员不足、部分商品发货较慢;(3)2020年“双十一”活动满意度为0.679 7,整体低于2021年,其中活动升级、物流进步使得满意度略有提升,但商品包装和直播间对满意度造成负面影响。     

基于“蚂蚁金服”事件网评文本的互联网金融监管蕴意挖掘

以“蚂蚁金服”事件网络评论为样本,借鉴生命周期理论划分评论发展阶段,运用词云图与语义网络进行文本特征可视化和关联分析,并基于LDA模型和语义情感分析考察各阶段评论主题演进趋势和特征,从而挖掘事件的互联网金融监管蕴意。研究表明:相关评论主题在不同阶段各有侧重,但总体呈现逐步细化、深入的特征;“平台垄断”“数据保护”主题最为突出;监管参与者范围扩大成为主要关注点;爆发和平息阶段的评论感情倾向变化较大。为此,互联网金融监管应注重平台防垄断、用户数据保护及多主体协同监管,重点关注爆发与平息阶段的互联网金融舆情引导。     

Social welfare in the light of topic modelling

With an increased focus on social well-being in response to a burgeoning global economy exposing the weaknesses of social welfare policies, research output in the field has grown exponentially. Keeping track of the evolving research themes proves difficult due to the steady rise in the number of studies published in the interdisciplinary field of social welfare. Therefore, researchers need a comprehensive overview to confirm the current shape of the field based on the published research. Using a latent Dirichlet allocation algorithm as a topic modelling technique, this study identified 12 prominent themes from more than 10,000 research outputs on social welfare published from 2000 to 2020 in Scopus-indexed journals. Such an exploratory text-mining approach to literature review provides broad insights into the diversity of research and may serve as a foundation for further in-depth studies. Identifying these 12 thematic areas and their sub-themes allows us to articulate the complexity and diversity of social welfare issues, which go far beyond the field of well-established welfare economics or social work. The study shows that the topic of ‘social welfare’ has not only evolved over time but has significantly broadened its meaning. It can no longer be solely synonymous with institutional social security. We contend that research in this area needs to take into account a broader and more systematic range of determinants constituting the dynamic character of social welfare.     

基于在线评论情感分析与LDA的物流服务质量影响因素研究

随着电子商务的迅速发展,商品在线评论的重要性日益凸显,成为影响消费者购买决策的关键要素之一.作为电子商务中的重要一环,物流服务相关评论的挖掘对提高消费者满意度和企业物流服务水平有着重要的意义.鉴于此,本文首先采用网络爬虫技术采集京东商城家电类、生鲜类和电子类商品的物流评论数据,运用Python 3.7对评论文本进行情感极性分类确定,最后通过对不同情感极性的评论文本进行词频分析和LDA主题模型分析发现,消费者对这三种类型商品物流服务需求的关注点存在明显不同.其中,家电类商品的安装和售后服务比较关键,消费者对生鲜类商品配送速度的要求较高,对电子类商品退换货服务关注度较高.商家和企业可以通过改善上述方面提升自身物流服务的质量,从而提高消费者满意度.     

政策与部门视角下中国网络空间治理——基于LDA和SNA的大数据分析

结合数据挖掘、主题建模、网络分析等多源融合的大数据分析法,针对网络空间治理政策及部门协同进行研究,对政策提升与机制优化具有重要意义。基于深度挖掘的网络空间政策文本,采用概率主题模型（LDA）从文本中发现并提取低维主题集合,分析主题分布;结合社会网络分析（SNA）,对出台政策涉及联合发文的部门开展合作网络分析;提取六项分类主题为指标,评估治理政策的布局特征;从部门合作网络整体结构和网络中心性两个维度,评估组织间协同合作效果,为政府政策优化和协同合作提供理论依据与决策建议。