基于EVA与经营风险偏好的供应链鲁棒优化模型

在由一个制造商和多个外部供应商构成的多产品、多阶段供应链中，将经济增加值（EVA）作为体现价值创造的绩效指标，并考虑决策者的经营风险偏好，采用已知概率的离散情景描述资本成本与需求的波动情况，利用鲁棒随机规划方法，建立了以价值创造为目标的供应链鲁棒优化模型。应用分析的结果表明，模型能够将供应链的绩效与风险管理结合起来，减少资本成本与需求不确定对目标值的影响，得到具有鲁棒性的最优解，而且越是风险厌恶型的决策者越会为了保持较低的经营风险而放弃较大的EVA值。同时，决策者可选择不同的权重系数侧重于解鲁棒或模型鲁棒，保证供应链运作的鲁棒性，实现价值创造的目标。     

考虑均值-方差风险量化的VMI供应链协调模型

针对众多企业风险规避的特性，构建了产出不确定环境下的供应链最优投入决策模型，并采用均值-方差模型来量化决策者的风险规避态度，讨论了风险规避的集成供应链和风险规避的VMI供应商在不同风险承受能力下的最优投入决策.研究表明，最优投入决策与其风险承受能力密切相关，且在给定风险承受能力下，决策者具有两种投入量备选方案.当选择低投入量所需承担的缺货损失低于选择高投入量所需承担的库存积压损失时，决策者将选择较低的投入量；否则，决策者将选择较高的投入量.本文进一步引入两种不同类型的契约来协调VMI供应链：成本共担-批发价折扣联合契约和期权契约.研究表明，这两种契约在一定条件下均能够协调VMI供应链，但这两种契约实现供应链帕累托改进的效果受到决策者风险承受能力的影响.     

基于活动方法的瓶颈模型与拥挤收费问题研究

Vickrey提出的基于出行的瓶颈模型以出行作为分析单位,没有考虑出行与活动之间的相互关联.本文对Vickrey的瓶颈模型进行了拓展,提出了基于活动的瓶颈模型来研究通勤者早晨上班出发时间决策问题,模型考虑了通勤者对出行负效用与活动效用之间的权衡.在基于活动的瓶颈模型的基础上,分别研究了常数和线性边际活动效用下瓶颈动态拥挤收费和阶梯收费问题,并与传统的瓶颈模型的解进行比较.结果表明,当活动的边际效用为线性函数时,瓶颈处最优动态收费曲线不再呈分段线性关系,而是分段二次曲线;与基于活动的瓶颈模型相比,传统的基于出行的瓶颈模型将高估瓶颈处的排队延误、阶梯收费水平,以及早高峰的开始和结束时间;基于出行的瓶颈模型和常数边际活动效用下的瓶颈模型导致的最优阶梯收费是最优动态收费最大值的一半,并且刚好消除瓶颈处排队延误的一半;与线性边际活动效用下的瓶颈模型相比较,两者低估了阶梯收费能消除的瓶颈排队,从而低估了阶梯收费的效率.     

基于似然估计的零售商库存鲁棒均值-风险模型

针对具有风险厌恶的零售商,建立了权衡期望利润和条件风险值（CVaR）的均值-风险库存优化模型,给出了离散需求分布不确定条件下能实现帕累托最优但具有较高保守性和非帕累托最优但具有较低保守性的两种鲁棒对应。针对不确定需求分布,在仅知历史需求样本数据情况下,应用统计推断理论构建了满足一定置信水平的基于似然估计的需求概率分布不确定集。在此基础上,运用拉格朗日对偶理论,将上述两种鲁棒对应模型转化为易于求解的凹优化问题,并证明了其与原问题的等价性。最后,针对实际案例进行了数值计算,分析了不同系统参数和样本规模对零售商最优库存决策及其运作绩效的影响,并给出了零售商期望利润和条件风险值两个目标权衡的帕累托有效前沿。结果表明,采用基于似然估计的鲁棒优化方法得到的零售商库存策略具有良好鲁棒性,能够有效抑制需求分布不确定性对零售商库存绩效的影响。而且,历史需求样本规模越大,鲁棒库存策略下的零售商运作绩效越接近最优情况。进一步,通过对比发现,两种鲁棒对应模型虽然保守性不同,但在最终库存策略上保持一致。     

面向动态出行需求的出租车运营系统仿真模型

基于离散事件仿真技术,提出一种面向动态出行需求的城市出租车服务模型。该模型可再现出租车在城市中24小时提供出行服务的动态过程。仿真结果表明,考虑时变特性能够得到出租车运营系统更真实和精确的信息;乘客队长和乘客平均等待时间是衡量出行需求是否动态满足的重要指标。研究了出租车数量和动态出行需求对系统性能的影响,给出了确定系统最优的出租车数量的方法,该方法能够兼顾运营商和乘客的利益。模型既可以为出租车监管部门提供决策依据,也有助于运营商提高运营效率。     

概率预期下在线报童问题的最小风险策略

报童问题是库存管理中一个基本模型。已有的报童模型主要利用均值-方差方法和期望效用目标方法进行风险的描述和度量。这些方法假设需求分布信息已知,而实际中需求分布信息往往难以完全刻画。本文使用概率预期作为刻画不完全需求分布信息的格式,基于在线风险补偿的思想,为需求分布信息不完全的报童问题建立了最小风险模型。使用该模型设计了最小风险策略,使报童可以根据自己设定的不同收益和未来概率预期选择最优订购量。     

考虑碳排放成本的差异化停车券管理研究北大核心CSCDCSSCI

给定允许公交车和轿车两种交通模式出行的双模式单起讫点的交通系统,以瓶颈模型为基础,考虑停车位的空间位置分布,提出了两种停车券管理策略:一是指定车位停车券策略;另一是不定车位停车券策略。两种形式均可以确保持券用户在停车场停车的权利,但前者进一步限定了轿车停车的位置。结合动态拥挤收费机制,以最小化系统出行成本和交通系统碳排放成本为目标进行策略优化研究,研究表明停车券管理策略可以消除停车位供给不足导致的停车竞争,降低轿车出行成本。此外,指定车位停车券和动态拥挤收费的综合实施可以实现系统最优。为了便于实施,并考虑公众的可接受性,只发放不定车位停车券也可以成为效率比较高的次优方案。     

考虑碳排放成本的差异化停车券管理研究

给定允许公交车和轿车两种交通模式出行的双模式单起讫点的交通系统,以瓶颈模型为基础,考虑停车位的空间位置分布,提出了两种停车券管理策略: 一是指定车位停车券策略;另一是不定车位停车券策略． 两种形式均可以确保持券用户在停车场停车的权利,但前者进一步限定了轿车停车的位置． 结合动态拥挤收费机制,以最小化系统出行成本和交通系统碳排放成本为目标进行策略优化研究,研究表明停车券管理策略可以消除停车位供给不足导致的停车竞争,降低轿车出行成本． 此外,指定车位停车券和动态拥挤收费的综合实施可以实现系统最优． 为了便于实施,并考虑公众的可接受性,只发放不定车位停车券也可以成为效率比较高的次优方案．     

模糊随机不确定环境下考虑决策者主观判断的亚式期权定价

考虑金融市场的不确定性包含随机性和模糊性两个方面,把标的资产价格视作一个模糊随机过程,以连续几何平均亚式看涨期权为例运用随机分析和模糊集理论研究了模糊随机不确定环境下的亚式期权定价问题。首先,推导出了亚式期权模糊价格的任意水平截集,并将如何计算给定任一个参考价格的置信度问题转化为求解最优化问题。然后,研究了两种考虑决策者主观判断的亚式期权定价,一是引入模糊目标表示决策者对期权预期价格的满意度,给出可靠度大于决策者满意度的亚式期权预期价格的范围;二是引入悲观-乐观指数表示决策者的悲观程度,基于加权函数和可能性估计测度定义模糊数的可能性均值,得到可能性均值意义下的亚式期权定价公式。最后,给出了一个数值例子说明了模型的可行性和实用性。     

设施失灵风险下不确定需求应急定位-路径鲁棒优化研究

为抵御突发灾害对路网造成的破坏性和设施失灵风险,降低系统成本,并快速完成应急救援任务,本文考虑到受灾点物资需求量的不确定和风险对救援系统的影响,采用直升机进行物资运送以规避路径风险。建立了最小化应急物流系统总成本和物资到达需求点总救援时间为双目标的应急物流定位-路径鲁棒优化模型,基于相对鲁棒优化方法处理需求不确定,采用偏差鲁棒优化思想描述设施失灵风险损失,采用遗传算法进行求解。通过对三个算例进行数据仿真实验,证明了相对鲁棒优化方法在处理需求不确定和偏差鲁棒优化方法在处理设施失灵风险方面的有效性,进而为解决应急设施点的开设和救援物资的安全及时准确配送,增强应急物流系统的风险应对能力提供了有效的方法。     

Power,authority and legitimacy

Management, human resources, organization, control, leadership, etc., all seem to be just so many euphemisms for power, and this suggests a discourse of management and organization that calls things by their proper name. This paper on the contrary stresses the need to resolve the concept of ‘power’ itself into more differentiated notions, and proposes that clarification may be derived from distinctions once explicit in the vocabulary of Classical antiquity, but lost in modern European languages. It argues that nothing but confusion in thinking about organizations, management and legitimation can result from the failure to recognize that the phenomena this vocabulary identifies and distinguishes are irreducibly different.     

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.     

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.