用聚类预报模型预报三峡水库来水量的探讨

为了开展三峡水库入库来水量长期预报,从北半球500 hPa高度场、太平洋海温场、北半球100 hPa高度场、北半球地面气压场与74项环流特征指数作为预报因子,采用回归方程求解和回归效果检验,建立回归聚类预报物理模型,对三峡水库6～8月各月平均来水量进行了长期预报分析。结果表明,三峡水库6~8月份各月来水量回归聚类预报的技术路线是可行的,正、负距平符号一致的概率能达到80%以上,效果较好,基本上可以满足生产需要。回归聚类预报物理模型具有一定的应用推广价值。     

分层递阶雨水情信息系统的应用研究

针对现有雨水情系统存在稳定性、可靠性和智能性方面的问题,基于Saridis提出的智能控制理论,设计了分层递阶雨水情信息系统。该系统在现有两级系统的基础上,增加了专门处理雨水情信息的嵌入式设备,搭建了遥测终端与雨水情应用平台的联系桥梁,使遥测终端和雨水情应用平台分工、功能更加明确,新系统提高了原有系统的稳定性、可靠性,可根据任务执行情况的反馈信息,并及时更新决策方案,因此,智能化程度更高。     

基于ACC-RBF的水布垭面板堆石坝参数反演分析

蚁群聚类径向基函数(ACC-RBF)神经网络是将蚁群聚类算法和径向基函数神经网络组合运用的一种新型神经网络模型,把该网络用于水布垭高面板坝堆石体的多参数反演问题,在室内试验参数的基础上用有限元计算获得学习样本,采用该网络对坝体堆石料的邓肯E-B模型参数进行反演分析,用反演所得参数结合三维非线性有限元计算坝体应力变形,并与实测资料比较,得出很接近的结论.     

ENVIRONMENTAL DETERMINANTS OF WATER QUALITY IN BOREAL RIVERS BASED ON PARTITIONING METHODS

Quantitative studies of the relationships between river water quality and environmental variables are needed to improve understanding of the impacts of natural and human factors on aquatic environments. However, multicollinearity between environmental variables can hinder the identification of key factors when water quality–environment relationship is studied using traditional regression methods. This study utilized two alternative statistical methods, variation and hierarchical partitioning, to address these difficulties in studies of river water quality. Using these methods, we explored the effects of catchment physiography, climate and land use variables on total phosphorus and nitrogen, pH, water colour and dissolved oxygen during the years 1995–2005 in 32 boreal rivers in Finland. Catchment physiography and land use explained most of the variation in water quality, especially in phosphorus, nitrogen and water colour data. The strong correlations (r_s > 0.8) between agricultural land use and phosphorus and nitrogen concentrations indicate that water quality is highly affected by agriculture in boreal regions. By determining the environmental drivers of different water quality variables, we can estimate the water quality of different catchments in response to environmental changes and identify areas that are sensitive to global changes. Our study shows that novel statistical methods integrated with geographic information system data and techniques provide deeper insights into water quality–environment relationships than traditional regression, and these should be considered when developing, for example, conservation planning for rivers. Copyright © 2011 John Wiley & Sons, Ltd.     

基于可变集聚类理论的年径流聚类新方法

将可变集中的聚类理论与年径流分类研究相结合,提出了年径流量聚类新方法。新方法考虑了汛期径流量、汛期向枯水期过渡的中介期径流量、枯水期径流量等因子或指标对年径流量分类的不同影响。通过实例分析,比较了新方法与常规方法（均值标准差法）和集对分析分类法的异同,表明新方法在理论与实际应用上的合理性与科学性,可应用于水文水资源系统年径流丰枯分类;最后分析了常规法、集对分析分类法在年径流分类中存在的问题及其理论根源。     

保定市农业节水分区

针对保定市水资源短缺、农业用水量大的现状,在综合分析地形地貌、气候特征、水资源利用状况以及农业结构等因素的基础上,采取系统聚类和主成分分析的方法进行农业节水分区的研究。依据确定的节水分区原则,筛选出15项原始指标,运用主成分分析法将15项指标表示成6个主成分,以提高计算效率;运用系统聚类法将保定市23个县划分成6个农业节水区,并结合自然、社会、经济情况对各区进行了分析,对各区农业节水措施给出相应的对策建议。     

Spreads, Depths, and Quote Clustering on the NYSE and Nasdaq: Evidence after the 1997 Securities and Exchange Commission Rule Changes

This paper examines liquidity and quote clustering on the NYSE and Nasdaq using data after the two market reforms—the 1997 order–handling rule and minimum tick size changes. We find that Nasdaq–listed stocks exhibit wider spreads and smaller depths than NYSE–listed stocks and stocks with higher proportions of even–eighth and even–sixteenth quotes have wider quoted, effective, and realized spreads on both the NYSE and Nasdaq. This result differs from the findings by Bessembinder (1999, p. 404) that "trade execution costs on Nasdaq in late 1997 are no longer significantly explained by a tendency for liquidity providers to avoid odd–eighth quotations," and "odd–sixteenth avoidance has little relevance for explaining post–reform Nasdaq trading costs."     

Using clustering ensemble to identify banking business models

The business models of banks are often seen as the result of a variety of simultaneously determined managerial choices, such as those regarding the types of activities, funding sources, level of diversification, and size. Moreover, owing to the fuzziness of data and the possibility that some banks may combine features of different business models, the use of hard clustering methods has often led to poorly identified business models. In this paper we propose a framework to deal with these challenges based on an ensemble of three unsupervised clustering methods to identify banking business models: fuzzy c‐means (which allows us to handle fuzzy clustering), self‐organizing maps (which yield intuitive visual representations of the clusters), and partitioning around medoids (which circumvents the presence of data outliers). We set up our analysis in the context of the European banking sector, which has seen its regulators increasingly focused on examining the business models of supervised entities in the aftermath of the twin financial crises. In our empirical application, we find evidence of four distinct banking business models and further distinguish between banks with a clearly defined business model (core banks) and others (non‐core banks), as well as banks with a stable business model over time (persistent banks) and others (non‐persistent banks). Our proposed framework performs well under several robustness checks related with the sample, clustering methods, and variables used.     

财务治理分层论

随着改革开放以来我国市场经济体制的改革与发展,现代企业财务制度不再是只由企业所有者单方包揽大局,而是由企业所有者、经营者和财务经理等分层对企业进行管理和治理,于是财务分层治理思想应用而生。     

华为负值PBGT切换技术应用

负值PBGT切换技术的实现和分层分级算法相似,但比分层分级算法更加灵活,它是移动通信系统中非常重要的技术。现通过工程实践多次使用网络优化工具设置负值PBGT切换参数,实现在双频网优化上的应用,可以避免乒乓切换引起掉话,该技术的应用有重要的现实意义。