Towards effective document clustering: A constrained K-means based approach

Document clustering is an important tool for document collection organization and browsing. In real applications, some limited knowledge about cluster membership of a small number of documents is often available, such as some pairs of documents belonging to the same cluster. This kind of prior knowledge can be served as constraints for the clustering process. We integrate the constraints into the trace formulation of the sum of square Euclidean distance function of K-means. Then,the combined criterion function is transformed into trace maximization, which is further optimized by eigen-decomposition. Our experimental evaluation shows that the proposed semi-supervised clustering method can achieve better performance, compared to three existing methods.     

环境约束下的中国城镇化效率及其影响因素研究

运用超越对数生产函数随机前沿模型,以2003—2010年中国279个地级及以上城市的面板数据为基础,将环境污染作为投入要素纳入城镇化效率评价体系,从人口、经济、空间、社会四个角度测算了环境约束下的中国城镇效化率,分析了环境约束下人口密度、产业结构、政府政策和市区规模等因素对城镇化效率的影响。结果显示:(1)比较而言,考察期间经济、空间及社会城镇化效率较高,人口城镇化效率较低,各类型的城镇化效率值在空间分布上整体呈现为东高西低的状态。(2)人口密度、产业结构和政府政策对人口及社会城镇化效率的影响均为正,而市区规模对前者的影响为负,对后者的影响则不显著;同时,市区规模对经济城镇化效率的影响也为负;产业结构和市区规模对空间城镇化效率的影响为正,人口密度为负。最后,本文建议,应通过统筹协调各影响因素来提升区域城镇化综合效率。     

融资约束对企业R&D投资影响的实证研究——基于产权与产业视角

使用沪深两市2009—2014年期间严格披露了研发支出信息的企业作为样本,采用FHP(1988)模型和构建融资约束指数检验企业RD投资中存在的融资约束,以及分析融资约束对RD投入的影响。研究结果表明,企业RD投资存在融资约束,并且融资约束制约RD投资;进一步分析融资约束在不同产权性质、不同产业性质企业中对RD投资的影响。结果发现,国有控股企业RD的融资约束小于非国有控股企业RD的融资约束;高新技术企业RD的融资约束小于非高新技术企业RD的融资约束。本文的研究结果可为政府和金融市场提供靶向性的金额支持政策提供决策参考。     

The geometry of linearly and quadratically constrained optimization problems for signal processing and communications

Constrained minimization problems considered in this paper arise in the design of beamformers for radar, sonar, and wireless communications, and in the design of precoders and equalizers for digital communications. The problem is to minimize a quadratic form under a set of linear or quadratic constraints. We present solutions to these problems and establish a connection between them. A majorization result for matrix trace and Poincare's separation theorem play key roles in establishing the connection. We show that our solutions can be formulated as generalized sidelobe cancellers (GSCs), which tie our constrained minimizations to linear minimum mean-squared error (LMMSE) estimations. We then express our solutions in terms of oblique projection matrices and establish the geometry of our constrained minimizations.     

Domesticating algorithms: An exploratory study of Facebook users in Myanmar

Abstract

This exploratory study investigates the encounters and everyday experiences with the Facebook algorithm of 18 informants in Yangon, Myanmar. It draws on domestication theory and research on algorithms to understand how users come to use and respond to Facebook. Findings showed that their particular perception of Facebook algorithm—Friends funnel information—informs their domestication process, wherein they add strangers as Friends to draw more information flows to their News Feeds.     

基于时间序列聚类的科研成果关键词分析方法

   鉴于传统方法对科研成果关键词研究存在较强主观影响和较少考虑时间因素等问题,提出基于时间序列聚类的科研成果关键词分析方法。该方法通过统计分析方法验证关键词出现顺序在一定程度上反映了关键词反映主题思想的重要性,将关键词的重要度转化为时间序列数据,分别从重要度的数值和趋势两个角度出发,使用动态时间弯曲方法度量关键词重要度时间序列数据之间的相似性,结合近邻传播方法对关键词时间序列数据之间的相似性矩阵进行聚类分析,实现科研成果的关键词分析研究。通过对某科研管理类重要期刊2008—2017年期间刊发的科研成果论文关键词研究发现：新方法不仅可以对科研成果中关键词的关注热度和趋势进行聚类划分,自适应地找到中心关键词作为相应类别的特征代表对象,还能为科研成果关键词的主题分析提供理论方法和决策支持。     

放松退耕地间种约束的政策合理性与有效性检验——基于贵州省新一轮退耕还林的农户调查

新一轮退耕还林在保护生态环境和促进农户增收方面被赋予重要期待。本文基于范围经济理论,利用贵州省的退耕农户调查数据,测算农户的间种的范围经济和范围利润水平,利用似不相关回归和面板Tobit模型分析间种对农户范围经济、范围利润和经济林管护的影响。研究发现,放松退耕地间种约束具有一定的合理性,但其有效性的发挥还需进行相应的政策调整。具体表现为：①双作物间种的范围经济水平高于单作物间种,经济作物间种的范围利润水平最高。具体的,“经济林+豆类+薯类”的范围经济值最高,平均值为0.835;“经济林+豆类”和“经济林+烤烟”的范围经济水平最低,平均值分别为0.205和0.142;“经济林+豆类”的范围利润值最低,平均为-0.457,“经济林+烤烟”的范围利润值最高,平均为0.908。②间种强度与范围经济、范围利润之间存在“倒U型”关系,间种并非越多越好;间种强度每增加1%,经济林的成活率会增加3.0%,但随着间种强度的增加,经济林的成活率将逐步下降;③相比间种粮食作物,种植经济作物更不利于经济林的管护。本文研究结果可为巩固新一轮退耕还林成果提供现实依据和理论参考。     

主成分聚类分析在行业统计数据中的应用

改革开放以来,在高速发展的中国经济带动下,各行各业有了飞跃的进步。当然,中国经济的发展也离不开各行各业认人士的辛勤劳动。虽然每个人从事的行业有所不同,但是每个人也都能在自己的行业上作出自己的贡献。文章以我国31个行政单位为研究对象,采用主成分聚类分析方法,运用spss19.0版软件,针对按照行业统计的31个行政地区的就业人数数据对31个行政地区进行聚类分析,表明了行业就业人数与地区的经济有关。     

林业可持续发展能力聚类分析的研究

通过聚类分析发现,云南林业整体在全国处于第七类地区,其典型特征即为"大资源小产业"。尽管云南森林资源丰富,生物多样性富集,但林业三大效益不均衡,其中生态效益较显著,而经济效益和社会效益很不显著。建设"森林云南"的重点是健全林业生态体系、优化林业产业结构、增强林业文化体系,以提升云南林业可持续发展能力。     

集群背景下我国造船企业战略成本管理模式

运用战略成本管理理念,结合我国造船企业的实际情况和集群市场环境的特点,提出了我国造船企业战略成本管理模式的构建原则与基本框架.在对集群背景下造船企业价值链和造船企业战略成本动因分析基础上,提出了集群背景下造船企业的战略成本定位,阐明了造船企业战略成本管理模式实施的保障措施.     

碳排放规制下中国主要工业行业全要素生产率研究——基于方向性距离函数与GML指数模型

为研究碳排放规制对我国工业行业节能减排的影响,本文基于方向性距离函数与GML指数模型,以2000-2012年中国36个工业行业的面板数据为样本,测度分析了碳排放规制对中国工业行业全要素生产率的影响。研究结果表明：碳排放规制有利于工业行业全要素生产率的增长,且规制条件越严格效果越明显;强碳排放规制下,技术效率得到了促进而对技术进步的影响不显著,对技术效率的促进是全要素生产率提高的动力,而弱碳排放规制对全要素生产率的提高机理相反。因此,碳排放规制强度的选择应综合考量当下的技术条件和不同行业效率特征,环境技术效率较低的工业行业更适合于严格的碳排放规制条件。这为碳排放规制政策运用到工业行业减排中的可行性提供了理论依据。     

Let’s search together,but not too close! An analysis of communication and performance in collaborative information seeking

Communication is considered to be one of the most essential components of collaboration, but our understanding as to which form of communication provides the most optimal cost-benefit balance lacks severely. To help investigate effects of various communication channels on a collaborative project, we conducted a user study with 30 pairs (60 participants) in three different conditions – co-located, remotely located with text chat, and remotely located with text as well as audio chat, in an exploratory search task. Using both quantitative and qualitative data analysis, we found that teams with remotely located participants were more effective in terms of being able to explore more diverse information. Adding audio support for remote collaboration helped participants to lower their cognitive load as well as negative emotions compared to those working in the same space. We also show how these findings could help design more effective systems for collaborative information seeking tasks using adequate and appropriate communication. We argue that collaboration is an important aspect of human-centered IR, and that our work provides interesting insights into people doing information seeking/retrieval in collaboration.     

浙江省县域科技创新活动的评估与空间聚集

文章评估了浙江省各县域科技创新活动的发展水平,分析了其空间聚集效应。在建立科技创新活动多指标综合评价体系的基础上,通过主成分分析法评价了浙江省90个县域2009~2012年的科技创新活动发展水平,并通过Moran’s I指数进一步分析了浙江全省以及各区县间的科技创新活动的空间聚集效应。结果表明:浙江省科技创新活动发展存在较明显的"东北崛起,西南塌陷"的空间格局,浙东北地区为科技创新活动发达聚集区,而浙西南为滞后聚集区。在时序上,区域创新活动水平总体呈稳定状态。创新活动发达区与滞后区的主要差距在于创新组织上。结论对于促进县域空间尺度的科技创新研究和实践具有一定的指导意义。     

Impacts of electronic process guides by types of user: An experimental study

The design and utilization of Electronic Process Guides (EPGs) have been studied in Software Engineering (SwE) since the 1990s. However, the empirical findings from surveys, case studies, and experiments on the beneficial effects of their utilization are still lacking. Thus, we suggest that further research on the utilization of EPGs is required. In this study, we are interested in gaining insights on the effects of using EPGs on objective metrics (learning score, time effort) and subjective metrics (perceived usefulness, ease of use, and value), by comparing three EPG designs (a simple PDF-based EPG, a normal HTML-based EPG, and a sophisticated Java-based EPG) with different blocks of experimental subjects (practitioners, academicians, novices, and experts). To this end, we have conducted a controlled experiment with a sample of international participants in the domain of IT Service Management. We found that the utilization of EPGs improves the objective metrics while no improvements were perceived on the subjective ones, and that the sophisticated EPG design is more appropriate for the academic and expert types of users than for the practitioner and novice types. Thus, our main recommendation for the design and utilization of EPGs is to consider the type of end-user.     

Role of oxidative stress in ethanol induced germ cell apoptosis — An experimental study in rats

The study was undertaken to evaluate the possible involvement of oxidative stress in the pathogenesis of ethanol induced testicular atrophy in rats. Adult male rats were orally administered ethanol at a dose of 1.6 g/kg body weight/day for four weeks. Twenty-four hours after the last treatment the rats were sacrificed using anesthetic ether. Testes were removed and weighed. Apoptosis was studied by using the Feulgen reaction on 5 μ thin paraffin sections of testis. Testicular homogenate was prepared and centrifuged. The supernatant was used for the estimation of extent of lipid peroxidation and antioxidant defense status. There was significant reduction in body weight: and in testicular weight and diameter in ethanol treated rats. Extent of germ cell apoptosis was significantly high in ethanol treated rats. Ethanol treated rats showed significantly high tissue TBARS level and glutathione S-transferase activity; and low tissue ascorbic acid, reduced glutathione, superoxide dismutase, catalase, glutathione peroxidase and glutathione reductase activities. Chronic ethanol administration resulted in high oxidative stress in the testes either due to increased extent of lipid peroxidation or due to decreased antioxidant defenses, and thereby induces germ cell apoptosis leading to testicular atrophy.     

Estimation of missing values in astronomical survey data: An improved local approach using cluster directed neighbor selection

The work presented in this paper aims to develop new imputation methods to better handle missing values encountered in astronomical data analysis, especially the classification of transient events in a sky survey from the Gravitational wave Optical Transient Observatory (GOTO) project. In particular, the framework of cluster directed selection of neighbors that has proven effective for benchmark local imputation techniques of KNNimpute and LLSimpute are extended to new multi-stage models. The proposed models, namely Iterative-CKNN and Iterative-CLLS, are novel with an original application to analyze sky survey data. They bring out advantages from both local approaches, where estimates are summarized from neighbors in the same data cluster, within the iterative process to refine previous guesses. Based on experiments with simulated datasets corresponding to different survey sizes and missing rations between 1 to 20%, they usually outperform baseline models and Bayesian Principal Component Analysis (BPCA), which is the well-known global technique. For instance, at 10% missing rate, Iterative-CLLS appears to be the most accurate with NRMSE score of 0.190, while BPCA and the best among its baseline models reaches 0.351 and 0.249, respectively. For their practical implications, these methods have proven to be effective for classifying transients, using common algorithms like KNN, Naive Bayes and Random Forest.     

高科技团队变革型领导、组织公民行为和团队绩效关系的实证研究

本文采用实证研究的方法探讨了高科技团队中团队领导者的变革型领导行为对团队成员的组织公民行为和团队绩效的影响作用。研究结果表明,关系导向的变革型领导行为对团队绩效具有显著的影响作用,变革型领导行为通过团队成员的组织公民行为对团队绩效发生影响,即组织公民行为在变革型领导与团队绩效之间起到中介作用。     

基于空间聚类分层抽样的黄骅市县域耕地质量等别监测样点布设

耕地质量监测是当前国家及时掌握耕地质量和产能变化的重要工作手段。合理布设耕地质量监测样点可以大幅提高耕地质量监测的效率。以河北省黄骅市县域耕地为研究对象,以耕地的质量属性和空间位置属性为耕地质量等别监测区的划定依据,采用空间聚类法生成20种备选监测区方案,通过综合比较方差、抽样误差、抽样效率和抽样弹性系数,选出初始监测区方案,并在此基础上局部优化,最终生成耕地质量等别监测区方案,最后以耕地质量等别监测区为分层依据,运用分层抽样法布设了耕地质量等别监测样点。研究表明：①在抽样误差为1%的要求下,分区数为65的备选耕地质量等别监测区方案的综合样本容量为77,抽样效率相对较高,被选定为初始监测区方案;②随着耕地质量等别监测区数目从5增加到100,相同监测区内耕地单元之间在空间位置和耕地质量等别上的差异程度由快速减少到趋于平稳;③在布设相同数量的监测样点时,本文提出的基于空间聚类分层抽样的样点布设方法在表土质地、剖面构型、盐渍化、有机质含量、排水条件、灌溉条件和国家耕地质量自然等指数等因素方面的抽样误差分别为0.37、1.02、1.39、0.91、0.31、1.53和1.27,均明显低于传统的等别分层抽样、简单随机抽样、网格分层抽样,具有较高的抽样效率。研究成果可为耕地质量等别监测样点布设相关工作和研究提供有效指导。     

技术联盟知识转移有效性影响因素的实证研究

为揭开技术联盟知识转移大量存在的"有转移行为,无转移效果"的管理决策"黑箱",尝试从知识、联盟企业和情境三个层面出发,在回顾现有相关研究文献的基础上,构建出技术联盟知识转移有效性影响因素的理论模型。通过问卷调查的方法收集国内201家企业的有效数据,选取统计分析软件SPSS16.0进行数据的信度、效度检验,采用基于最大似然估计法的结构方程建模软件LISEREL8.70进行理论假设的检验。实证研究结果表明,基础知识的关联性、专业知识的差异性、发送方的知识转移能力、接收方的知识吸收能力、联盟企业间的承诺皆对知识转移有效性具有显著的正向影响;联盟企业间的信任并不对知识转移有效性产生直接效应,而是通过承诺间接地对知识转移有效性产生正向影响。     

江苏省科技金融政策有效性的实证研究

选择江苏省13个省辖市的科技型企业作为研究对象,运用描述性统计和灰色关联度等方法对样本城市的科技企业绩效与政策绩效进行分析。研究结果显示,政策出台数量的多少与科技型企业发展的关联度最低,而高新技术企业孵化器数量是科技型企业发展最重要的影响因素,科技金融政策具有时滞效应和时间累积效应。