多标准决策表中发现概率规则的变精度粗糙集方法

用优势关系代替不可分辨关系,本文提出了一种可以从多标准决策表中获取概率规则的扩展变精度粗糙集模型,该模型能够处理多标准决策表中可能的不一相容性,获取由偏好对象组成的概率决策规则集,并导出事例决策系统的偏好模型。研究结果表明:基于优势关系,从多标准决策表中获取的最小概率规则集,使用的条件数量较少,且导出规则的数量较少、较强。     

基于粗集理论的一种归纳学习算法

归纳学习是粗集理论的主要应用领域.本文基于粗糙集理论,针对相容决策表,提出一种新的归纳学习算法.与以往的方法相比,这种算法比较简单,能够全面地获取规则且没有冗余.此外,还讨论了不相容决策表的学习,给出了具有较高可信度的规则挖掘过程.     

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.     

基于改进遗传算法的决策规则库自动维护与求精机制研究

智能决策支持系统的性能和决策质量的优劣取决于知识库的内容和运行情况,随着系统和问题的日益复杂,知识库的规模越来越庞大,内容越来越复杂,需要提供有效的方法实现其优化管理.对智能决策支持系统中规则库的运行特性和可能的潜藏缺陷进行归纳分析,提出一种将传统优化方法和遗传算法相结合的二级规则库维护与求精机制,可以较好地识别和消除8种规则库缺陷,提高知识库的运行效率和推理求解效果.对各环节给出了具体的操作算法,可以实现在专家少量参与下的规则库自动优化.     

遗传算法在库存模糊逻辑控制中的应用

本文结合库存模糊逻辑控制模型,提出了一种用遗传算法获取并优化模糊规则的新方法——二阶段学习算法,本方法可进化生成模糊规则,并结合实例,说明该算法解决的实际问题,指出其应用前景。     

基于粗糙集理论的格序选择方法

在粗糙集理论中,为了识别由偏好属性导致的不相容性,已提出基于优势关系的粗糙集理论,然而这一理论在实际应用中往往导致多个决策规则的出现,如何辨别由偏好多属性决策表中获取的多个决策规则从而选取最优方案,尚未见到有关的研究文献。本文针对这一问题,利用格序理论,给出属性约简的贴近度,比较不同约简所得决策规则贴近于原知识库的程度,从而得到一种选择最优决策方案的方法。     

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     

基于状态空间图的规则优化

在专家系统中,专家的知识通常是以规则的形式存在,不言而喻,规则的数量和质量决定了系统的处理能力,因此系统的规则优化问题也就成为了建造专家系统的议题之一.本文基于状态空间图提出了优化规则系统的算法,以达到降低系统的复杂性、加快系统响应速度、提高系统稳定性的目的.     

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。     

基于粗糙集理论的财务危机预警研究

本文针对财务危机预警中财务比率数量较多时计算量较大的问题,提出了基于粗糙集理论的财务危机预警模型,将财务比率分别作为条件属性,将企业所处的状态作为决策属性,从而构成一个财务预警决策系统.通过对决策表的属性约简和规则约简,得到决策系统的最小决策规则,从而实现财务危机预警.测试结果表明,该方法的预警结果正确、有效.     

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.     

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.     

Job strain and psychotropic drug use among white-collar workers

The main objective of this study was to measure the association between simultaneous exposure to high psychological demand and low decision latitude at work and the use of psychotropic drugs among white-collar workers. A second objective was to determine whether social support at work modified this association. A cross-sectional study was performed that included 2786 workers from the public sector in the Greater Quebec City area. A self-administered questionnaire was used in order to evaluate psychological demand, decision latitude and social support at work. Psychotropic drug use was measured over a period of 2 days. The prevalence of psychotropic drug use among the participants was found to be 3.9%, even though 20.5% were exposed to job strain. The association between job strain and psychotropic drug use, after adjustment for social support at work, age, gender, education, family income, employment status, occupation, stressful life events, cigarette smoking, alcohol consumption and physical activity, was statistically significant (odds ratio: 4.5, 95% CI 1.7?12.2). Social support did not appear to modify this association. The results of this study suggest that job strain might be a determinant of psychotropic drug use among white collar workers. Social support at work does not appear, however, to modify this association.     

Role clarity, work overload and organizational support: multilevel evidence of the importance of support

The present study extended the demands-control-support model used in occupational stress research in two ways. First, it hypothesized that role clarity (i.e. role ambiguity), like control, would moderate the relationship between demands and psychological strain. Second, the study assessed support (from leaders) as a macro characteristic of the work-group environment. Data were drawn from a large study of US army soldiers, the study sample consisting of 1786 lower enlisted male soldiers. The inclusion of support as a work-group characteristic lead to a multilevel test of the model. A three-way multilevel interaction among work demands, role clarity and support was observed. As predicted, the relationship between demands and psychological strain was moderated by role clarity; however, this moderating relationship was found only when work-group support was high.     

Leadership, levels of analysis, and déjà vu: Modest proposals for taxonomy and cladistics coupled with replication and visualization

In the inaugural issue of LQ's Yearly Review of Leadership, Hunt and Dodge (2000, p. 442) note that, “Within the last two decades, one of the crucial developments in organizational research in general, and in leadership research specifically, is the articulation of specific levels of analysis and their implications for theory building, measurement, and observation.” Their original observations are updated by extending the inferential logic of Yammarino, Dionne, Chun and Dansereau (2005) to determine if any increase in the utilization of a level of analysis perspective has occurred in the last five years. The possible evolution of leadership theory and analysis is discussed, especially with reference to Relational Leadership Theory, Leader–Member Exchange, and Individualized Dyadic Theory. Proposals incorporating taxonomic and visualization tools as a means to help bridge the stakeholder gap are also offered.     

Information Frictions in Trade

It is costly to learn about market conditions elsewhere, especially in developing countries. This paper examines how such information frictions affect trade. Using data on regional agricultural trade in the Philippines, I first document a number of observed patterns in trade flows and prices that suggest the presence of information frictions. I then incorporate information frictions into a perfect competition trade model by embedding a process whereby heterogeneous producers engage in a costly sequential search process to determine where to sell their produce. I show that introducing information frictions reconciles the theory with the observed patterns in the data. Structural estimation of the model finds that information frictions are quantitatively important: roughly half the observed regional price dispersion is due to information frictions. Furthermore, incorporating information frictions improves the out‐of‐sample predictive power of the model.     

The Economics of Density: Evidence From the Berlin Wall

This paper develops a quantitative model of internal city structure that features agglomeration and dispersion forces and an arbitrary number of heterogeneous city blocks. The model remains tractable and amenable to empirical analysis because of stochastic shocks to commuting decisions, which yield a gravity equation for commuting flows. To structurally estimate agglomeration and dispersion forces, we use data on thousands of city blocks in Berlin for 1936, 1986, and 2006 and exogenous variation from the city's division and reunification. We estimate substantial and highly localized production and residential externalities. We show that the model with the estimated agglomeration parameters can account both qualitatively and quantitatively for the observed changes in city structure. We show how our quantitative framework can be used to undertake counterfactuals for changes in the organization of economic activity within cities in response, for example, to changes in the transport network.     

Modelling end-of-life product recovery chains - a case study

European Union legislation, and existing national legislation of many European countries, mandates that manufacturers take back and recover their electronic and electrical equipment. If manufacturers are to comply with legislation, models need to be developed for these activities. Whilst infrastructural and technological deficits exist and must be addressed, so too must the organization of recovery, from a business perspective. In this paper, models of resource recovery are presented and a case study described.