智能决策支持系统中定量特征规则的挖掘方法研究

定量特征规则通过将定量信息与规则相结合定量地反映了概念的主要特征和次要特征,面向属性的归纳学习算法是在数据库中挖掘定量特征规则的一个重要手段,但直接采用这种方法往往会使同一个概念有不同的特征描述,这种现象必然降低规则对决策的参考价值.本文提出了一个测量定量特征规律有效性的计算指标,并结合该指标设计出一个新的面向属性的归纳算法,该算法使定量特征规则在有效性上达到最优,避免了同一概念有不同的特征规则的现象.     

在数据库中挖掘定量关联规则的方法研究

数据挖掘技术是实现智能决策支持系统的一个重要手段 ,关联规则是数据挖掘的一个重要内容 .传统的 Apriori算法仅适用于挖掘数据间的定性关联关系 ,但数据间的定量关联关系对决策更有帮助 .属性值的离散映射是挖掘定量关联规则的一个重要环节 ,离散映射中属性值区间的划分粒度是影响数据挖掘质量的一个重要因素 .本文结合粗集理论提出了一个确定属性值划分粒度的方法 ,在此基础上设计出一个挖掘定量关联规则的算法 :Apriori 2 ,利用Apriori 2可以挖掘出大量对决策有帮助的定量关联规则     

基于蚁群算法的群体用户兴趣导航路径发现

在电子商务的发展进程中,如何准确理解用户访问网站的行为是一个紧迫的问题.Web使用挖掘是解决该问题的重要研究方法.发现用户的兴趣导航模式是Web使用挖掘的一个重要研究领域,也是优化Web站点框架设计的根本方法.在本文中,我们把Web用户看成是人工的蚂蚁,应用蚁群算法来发现用户的导航模式.首先,建立了一个Web站点模型;然后基于蚁群算法和Web日志数据建立了一个用户导航模型;最后,设计了一个算法,将所有的访问用户视为整体来挖掘他们偏好的导航路径.实验结果表明该方法能准确反映出用户的浏览兴趣.     

基于意外度的关联规则深层知识发现及应用研究

为了弥补传统关联规则挖掘产生大量冗余规则、难以直接用于决策支持的不足,本文提出了一种基于用户已有知识的规则意外度评价方法,并在此基础上设计了基于意外度的深层关联规则挖掘算法。算法的优点在于能够将用户已知的规则作为领域知识加入到数据挖掘过程从而有效过滤和已知规则相近的冗余规则,并且可以将新得到的规则加入知识库中实现知识的积累和重用。最后本文采用一个商场数据验证了该算法的有效性,并且对具有回馈模式的关联规则在商品促销中的作用进行了分析。     

基于XML的通用关联规则挖掘应用模式

本文分析了关联规则挖掘应用中在通用性、用户简易性以及可扩展性方面所面临的一些困难,提出了一种基于XML的通用关联规则挖掘应用模式。该模式充分利用了XML在自描述能力、异质系统数据交换能力以及可扩展性方面的优势,提供了一个模块化、易于集成、适合于最终用户使用的应用框架。     

中文网络客户评论的产品特征挖掘方法研究

随着互联网的广泛应用,在Blog、BBS、Wiki等网络站点中出现了大量的针对商品或服务的客户评论,这些客户评论中所包含的丰富信息,对企业管理具有重要的价值.通过数据挖掘算法对客户针对某一产品的大量评论进行分析,可以挖掘出这些产品的主要特征,并有望进一步发现客户对这些特征的意见和态度.在英文世界中已经有学者开始对这一研究进行探索,然而由于语言结构等方面的差异,英文的研究成果尚无法直接应用于中文客户评论的挖掘中.本研究针对中文的特点,提出了面向中文的客户评论挖掘方法.该方法基于改进关联规则算法实现了针对中文产品评论的产品特征信息挖掘.本研究采用通过互联网获得的针对手机、数码相机、书籍等5种产品的评论语料,对该方法进行了数据实验,实验结果初步验证了该方法有效性.     

基于正相关关联规则挖掘分析的客户需求权重预测

为预测经营活动中的客户需求,提出一种基于正相关关联规则的数据挖掘模型.挖掘统计数据的频繁2_项集并对挖掘结果剪枝处理,按照特征需求重要性大小,计算得出重要客户需求,再运用BP神经网络进行需求权值预测.实例表明该方法可减少关联规则数量和挖掘工作量,对需求的预测具有现实意义.     

基于关联规则算法的电力企业财务信息异常数据智能挖掘方法

常规的电力企业财务信息异常数据挖掘方法以集群挖掘与分段挖掘为主,同一类别的异常数据挖掘效率较低,影响财务数据整合效果。因此,本文设计了基于关联规则算法的电力企业财务信息异常数据智能挖掘方法。此方法标注电力企业财务信息数据挖掘异常点,建立电力企业财务信息数据集,逐步探查数据集中的异常数据,并将异常数据汇总到一个数据单元中,形成财务信息数据异常点。本文基于关联规则算法挖掘电力财务异常频繁项集,在电力财务数据异常点中,挖掘出存在价值的信息,确保异常数据挖掘的准确性。采用对比实验,验证了该方法的数据挖掘准确性更高,能够应用于电力企业财务管理工作中。     

一类表间多层次关联规则挖掘算法研究

关联规则采掘是数据挖掘及其应用研究中的重要内容之一.本文提出了多表间多概念多层次关联规则挖掘问题,研究了相关的挖掘算法,对所提出的算法进行了初步分析.该算法应用于某营销经理信息系统的关联规则挖掘,获得的结果表明算法是实用和有效的.     

面向电子商务的Web挖掘系统模型研究

在电子商务网站中,Web使用挖掘可以通过分析Web日志等数据源来获取与用户访问模式相关的信息。本文主要研究电子商务中的Web挖掘技术,提出一个面向电子商务站点的Web挖掘系统模型。     

Introduction to Special Section on Sensitivity Analysis and Summary of NCSU/USDA Workshop on Sensitivity Analysis

This guest editorial is a summary of the NCSU/USDA Workshop on Sensitivity Analysis held June 11–12, 2001 at North Carolina State University and sponsored by the U.S. Department of Agriculture's Office of Risk Assessment and Cost Benefit Analysis. The objective of the workshop was to learn across disciplines in identifying, evaluating, and recommending sensitivity analysis methods and practices for application to food‐safety process risk models. The workshop included presentations regarding the Hazard Assessment and Critical Control Points (HACCP) framework used in food‐safety risk assessment, a survey of sensitivity analysis methods, invited white papers on sensitivity analysis, and invited case studies regarding risk assessment of microbial pathogens in food. Based on the sharing of interdisciplinary information represented by the presentations, the workshop participants, divided into breakout sessions, responded to three trigger questions: What are the key criteria for sensitivity analysis methods applied to food‐safety risk assessment? What sensitivity analysis methods are most promising for application to food safety and risk assessment? and What are the key needs for implementation and demonstration of such methods? The workshop produced agreement regarding key criteria for sensitivity analysis methods and the need to use two or more methods to try to obtain robust insights. Recommendations were made regarding a guideline document to assist practitioners in selecting, applying, interpreting, and reporting the results of sensitivity analysis.     

Distinguishing traumatic, vicarious and routine operational stressor exposure and attendant adverse consequences in a sample of police officers

Problems in studying occupational stress within the police service are identified and the paucity of work on operational duties as potential stressors are discussed. The present study reports the results of a factor analysis of operational stressors (N = 601 serving British police officers) that revealed three factors: exposure to death and disaster; violence and injury; sexual crime. These were demonstrated to be reliable scales and were included in logistic regression models together with a range of demographic and psychological variables. Models were applied to men and women separately, which showed there to be different predictors of the likelihood of suffering distress (measured by the General Health Questionnaire, GHQ) in terms of the officer's gender and operational role. Overall the model for women officers was better at predicting psychological distress than that for men. These findings are related to aspects of the police occupational culture. Further discussion is offered that conceptualizes police operational stressors as traumatic, routine and vicarious. Finally, some implications are drawn for the provision of stress intervention in the light of this differentiation.     

Criteria for selecting a production control philosophy

Logistic objectives constitute a compromise between having short leadtimes and a low volume of work in progress on the one hand and a high resource loading and due date obligation on the other. Miscellaneous production planning approaches offered today provide different combinations of logistic objectives for satisfying a manufacturing strategy. To combine the strength of the various approaches into a unified system, a new approach based on a dynamic and distributed production planning methodology is proposed. To customize the approach, various analyses and specifications have to be made and for that reason some important characteristics and criteria for analysing production control philosophies will be given.     

The social construction of the meaning of acute stressors: a qualitative study of the personal accounts of police officers using a stress counselling service

The police profession is one in which acute stressors are encountered more frequently than in other occupations. Using the personal accounts of 35 police officers attending an in-house stress counselling clinic, the aim of the present study was to provide a qualitative examination of how the institutional context of policing influenced the ways in which acute stressors signified to individual police officers experiencing felt distress. Using the framework of Rational Emotive Behaviour Therapy as an analytical tool, it is argued that beliefs contributing to the experience of felt distress are related to the way in which policing as both an identity and an activity is constructed through the police organizational culture. Not only do these constructions influence the ways in which officers perceive themselves and their environments, but they also operate at the collective level to 'normalize' some emotional responses and to 'pathologize' others which, it is argued, could impact upon the outcomes of interventions such as stress counselling.     

The moderating role of social support in Karasek's job strain model

This paper examines whether social support is a boundary-determining criterion in the job strain model of Karasek (1979). The particular focus is the extent to which different sources of social support, work overload and task control influence job satisfaction, depersonalization and supervisor assessments of work performance. Hypotheses are tested using prospective survey data from 80 clerical staff in a university setting. Results revealed 3-way interactions among levels of support (supervisor, co-worker, non-work), perceived task control and work overload on levels of work performance and employee adjustment (self-report). After controlling for levels of negative affect in all analyses, there was evidence that high levels of supervisor support mitigated against the negative effects of high strain jobs on levels of job satisfaction and reduced reported levels of depersonalization. Moreover, high levels of non-work support and co-worker support also mitigated against the negative effects of high strain jobs on levels of work performance. The results are discussed in terms of the importance of social support networks both at, and beyond, the work context.     

Job insecurity, coping resources and personality dispositions in occupational strain

This paper presents research on the relationships between the work-related stressor of perceived job insecurity and various indicators of occupational strain, taking into account employees' personality dispositions (trait negative and positive affectivity) and coping resources. Respondents were 222 Australian public servants surveyed during organizational restructuring that involved downsizing and threat to job certainty. The research was formulated within an adaptation of Osipow, Doty, and Spokane's (1985) framework of stress-strain-coping that included the possible direct as well as moderating effects of personality dispositions in reporting occupational strain (Parkes, 1990). Findings from hierarchical regression analyses indicate consistent significant independent effects of personality dispositions, coping resources and perceived job insecurity on various indicators of strain. There was also support for the moderating roles of negative affectivity and self-care in the relation between perceived job insecurity and physical strain. Implications for the role of dispositional factors, especially negative affectivity, and the utility of various coping resources in accounting for occupational strain in times of threatened job security are discussed.     

Job stress, job strain, and psychological withdrawal among Dutch university staff: towards a dualprocess model for the effects of occupational stress

This study examined the antecedents of job strain (emotional exhaustion, health complaints) and withdrawal behaviour (e.g. lowered organizational commitment) among a cross-sectional sample of 131 academic staff members of the law department of a large Dutch university. Conservation of resources theory (Hobfoll, 1989) provided the theoretical background for this study. Strains and withdrawal behaviours were expected to be most prominent among those who reported having few resources and/or who reported high job demands. Structural equation modelling revealed that this was indeed the case. As predicted, differential patterns of effects emerged for job demands and job resources. Analysis of the effects of four job-specific stressors revealed that especially the structural aspects of a staff member's teaching task (e.g. the number of students in their classes) contributed strongly to perceived job demands. Theoretical and practical implications of the study are discussed.     

Dermal Uptake of 18 Dilute Aqueous Chemicals: In Vivo Disappearance‐Method Measures Greatly Exceed In Vitro‐Based Predictions

Average rates of total dermal uptake (K_up) from short‐term (e.g., bathing) contact with dilute aqueous organic chemicals (DAOCs) are typically estimated from steady‐state in vitro diffusion‐cell measures of chemical permeability (K_p) through skin into receptor solution. Widely used (“PCR‐vitro”) methods estimate K_up by applying diffusion theory to increase K_p predictions made by a physico‐chemical regression (PCR) model that was fit to a large set of K_p measures. Here, K_up predictions for 18 DAOCs made by three PCR‐vitro models (EPA, NIOSH, and MH) were compared to previous in vivo measures obtained by methods unlikely to underestimate K_up. A new PCR model fit to all 18 measures is accurate to within approximately threefold (r = 0.91, p < 10^?5), but the PCR‐vitro predictions (r > 0.63) all tend to underestimate the K_up measures by mean factors (UF, and p value for testing UF = 1) of 10 (EPA, p < 10^?6), 11 (NIOSH, p < 10^?8), and 6.2 (MH, p = 0.018). For all three PCR‐vitro models, log(UF) correlates negatively with molecular weight (r² = 0.31 to 0.84, p = 0.017 to < 10^?6) but not with log(vapor pressure) as an additional predictor (p > 0.05), so vapor pressure appears not to explain the significant in vivo/PCR‐vitro discrepancy. Until this discrepancy is explained, careful in vivo measures of K_up should be obtained for more chemicals, the expanded in vivo database should be compared to in vitro‐based predictions, and in vivo data should be considered in assessing aqueous dermal exposure and its uncertainty.     

Systems Resilience for Multihazard Environments: Definition,Metrics, and Valuation for Decision Making

The United Nations Office for Disaster Risk Reduction reported that the 2011 natural disasters, including the earthquake and tsunami that struck Japan, resulted in $366 billion in direct damages and 29,782 fatalities worldwide. Storms and floods accounted for up to 70% of the 302 natural disasters worldwide in 2011, with earthquakes producing the greatest number of fatalities. Average annual losses in the United States amount to about $55 billion. Enhancing community and system resilience could lead to massive savings through risk reduction and expeditious recovery. The rational management of such reduction and recovery is facilitated by an appropriate definition of resilience and associated metrics. In this article, a resilience definition is provided that meets a set of requirements with clear relationships to the metrics of the relevant abstract notions of reliability and risk. Those metrics also meet logically consistent requirements drawn from measure theory, and provide a sound basis for the development of effective decision‐making tools for multihazard environments. Improving the resiliency of a system to meet target levels requires the examination of system enhancement alternatives in economic terms, within a decision‐making framework. Relevant decision analysis methods would typically require the examination of resilience based on its valuation by society at large. The article provides methods for valuation and benefit‐cost analysis based on concepts from risk analysis and management.     

Employees' perceptions of organizational restructuring: the role of social support

Organizational change and restructuring is often perceived as leading to increased occupational stress, impacting negatively on the psychological well-being of employees. This pragmatic study investigates the role of social support and dispositional affect as moderators of role stress post-restructuring for employees in a public utility company. A total of 176 employees, including 37 managers, 60 graded staff and 78 industrial staff completed a self-report questionnaire, approximately 1 year postrestructuring, retrospectively assessing role conflict, ambiguity, overload and positive and negative feedback pre- and post-restructuring. Results suggested that overall role stress increased for managers/ senior officers and graded staff, but not for industrial staff. Social support was linked with lower role stress, more positive feedback and less negative feedback at post-restructuring. For certain role stressors this impact was moderated by dispositional affect, but the effect was not consistent across occupational groups. Positive affect enhanced the effect of manager support in reducing role conflict for graded staff, and the effect of co-worker support in increasing positive feedback and reducing negative feedback for industrial staff. Findings suggest that managers should pay particular attention to support and feedback for employees during periods of chronic occupational stress following organizational restructuring.