基于有限理性假设的秘书问题研究

已有解决秘书问题的方法主要是以取样选项中的最大值作为标杆,其优点是能保证赢的概率最大,但很少考虑决策者的有限理性与启发式偏见.探索性地提出截止阀法则的均值标杆与次大值标杆策略的设想,通过计算机仿真实验与理论求解验证与比较了该策略的特征与规律.结果发现,均值标杆的决策最优度明显优于最大值标杆,决策最优度随标杆变动呈U型曲线变化趋势,最高点是均值标杆20%及其附近,赢的概率随着标杆的降低而逐渐减少,且最优截止阀值也不断后移.     

动态决策过程中备选项的序列特征效应研究

动态决策过程中备选项随机出现的序列特征,可以分为较优选项连续出现、间隔出现以及较劣选项连续出现等特征.运用实验室实验的方法研究发现,当较优选项连续出现时会"启发"决策者产生"手热"认知心理偏差,进而导致较优选项连续出现的次数与决策者的搜索数量呈正相关关系.而当较劣选项连续出现时则会"启发"决策者产生"赌徒谬误"认知心理偏差,进而导致较劣选项连续出现的次数与决策者的搜索数量也呈正相关关系.这解释了在动态决策过程中,决策者面对较优或较劣选项连续出现的情境下,为何都采取继续观望等待的非理性决策行为.同时,对"手热效应"与"赌徒谬误"效应的差异性以及出现的情境进行了比较分析.     

取样观察值的离散程度对动态决策影响的实验研究

序贯观察和选择问题是一种动态的信息搜索和决策过程,基于决策者的有限理性假设和行为决策理论对搜索过程中选项值的特征信息效应进行研究.运用实验室实验的方法研究发现,序贯随机出现的选项值离散程度时人们的判断心理和决策行为具有影响作用选项值的整体离散程度与搜索数量呈负相关关系,而其局部急剧升高的离散程度则与发生选择的概率呈正相关关系.研究还发现,人们往往高估自己解决序贯观察和选择问题的能力,存在着明显的过度自信偏差.     

模糊需求VRP的一种Sweeping启发式算法

在对具有模糊需求的车辆路径问题(VRPFD)进行简单描述的基础上,结合模糊机会约束规划的基本给出了解决该问题的基本思路,构建了其数学规划模型,并设计了解决该问题的一种Sweeping启发式算法.埽在最小化车辆总行驶距离的目标下,通过随机模拟方法研究了决策者的主观偏好P*对最终决策目标的影响作并给出了P*的合理取值范围.     

一类序贯决策方法的提出:透镜与直觉模糊信息的视角

与大多数关注经典秘书问题的序贯决策研究不同,本文针对决策对象不变而其状态更新的一类序贯决策问题,提供决策方法。相较已有研究而言,本文从透镜与直觉模糊信息的视角提出这类序贯决策的一般方法,更加具有普适性,可应用于应急管理、风险投资等多个方向。该决策方法具有如下特点：1）借鉴透镜模型,通过当期可观测的线索,预测这类序贯决策问题的下一期状态;2）考虑到决策环境具有不确定性,采用直觉模糊数对决策者获取的信息线索进行刻画;3）为最大化模拟现实决策者,在前景理论框架下提出状态更新的序贯决策方法。本文提出的决策方法依据在于决策者对决策对象的预测"前景"值和预测绩效,基于此提出了具体的决策步骤,并辅以案例进行分析。通过对不同决策情形下决策结果的比较分析和对案例的稳健性检验,验证了该决策方法的适用性和有效性。     

消费者选择中后悔和不确定性的作用研究

研究当消费者对产品绩效的期望不确定性时,后悔如何影响消费选择的动态变化.数学分析和实验结果表明,当消费者观察或体验到的各个产品选项的表现与原先的期望相吻合,风险厌恶型消费者倾向于提高对初始期望绩效不确定性较高的产品的购买意愿,而风险喜好型消费者倾向于降低对该产品的购买意愿.另外,期望绩效水平的不确定性对消费选择的影响会随消费者经验值的增加而减小.研究成果弥补了现有期望差异理论对解释消费行为动态变化的不足.因此,为了更加全面地理解在多选项选择问题中后悔对消费选择的动态影响,管理者需要考虑备选产品在期望绩效水平不确定性上的差异、相关消费市场的顾客风险偏好构成、消费者的购买经验等特征.     

模糊需求信息条件下的实时动态车辆调度问题研究

将传统确定性车辆调度问题扩展为具有模糊特征的模糊车辆调度问题。在对模糊需求信息条件下的车辆调度问题进行简单描述的基础上,阐述了全面、实时地考虑所有可用信息的动态模糊车辆调度问题的求解思路,并通过引入决策者主观偏好和模糊可能性的概念,构建了该问题的数学模型,给出了解决该问题的一种实时启发式算法。最后,在最小化车辆行驶距离的目标下,通过随机模拟方法研究了决策者主观偏好值对最终决策目标的影响作用,并通过与非实时调度的比较验证了实时车辆调度的优越性。     

外生状态的信息与经典的柔性选择

将经典柔性决策模型中决策者的柔性选择与观察到的外生状态(信息)之间的比较静态关系进行了统一的考察,并且将相应的结果应用于实物期权投资模型和动态规划模型.这一比较静态关系表明,在一定的技术假定下,决策者利益函数的上模性(决策选择与外生状态之间的互补特性)对应于二者之间的同向变化,而决策者利益函数的子模性(决策选择与外生状态之间的替代特性)对应于二者之间的反向变化.这一结果统一了文献中存在的关于决策选择与观察到的外生状态之间的比较静态关系的具体结果,从而扩展了这些结果.     

一类两层规划问题模糊满意解的遗传算法

在现有两层规划问题求解方法的基础上,提出用浮点数编码的遗传算法求解该问题模糊满意解的新方法．这种方法每次提供给决策者一组近似最优解,通过决策者的比较、评价和选择,在交互过程中得到各决策者都满意的解．该方法不仅可以给决策者提供更多的决策环境信息,而且可以适应决策者偏好的变化,使得决策过程更合理,更符合人的认识过程．     

等待时间受限的流水车间调度问题的启发式算法

针对等待时间受限的流水车间调度问题,分析了等待时间上限与可行解的解析关系以及目标函数的特殊性质,以此为基础,提出了一种启发式算法.算法采用贪婪与插入相结合的启发式规则构造工件加工序列,通过递归回溯解消其等待时间受限约束.仿真实验表明,该启发式工件排序规则在等待时间约束较紧或问题规模较大时,较其他几种常用排序规则具有更好的效果.     

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.     

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.     

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.     

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.     

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.     

UNIX系统性能监控简述及shell系统资源统计程序

本文简要阐述了unix系统中(主要以IBM的AIX为例)进行系统性能管理的几种命令行工具,并通过编写shell实例程序,运用其中提到的工具实现系统资源利用率的统计程序,为做好unix系统管理和调优提供参考.