不确定JIT交货条件下供应链协调及主从对策问题研究

供应链中在不确定JIT交货条件下如何进行供应商与生产商之间的协调是一个十分重要的问题。考虑到供应链成员间决策的交互形式,本文在文[1]的供应商与生产商独立最优和联合最优的基础上提出了一种更具实际意义的供应链协调机制—Stackelberg主从对策,推导了Stackelberg均衡解。文中以上海宝钢集团企业开发总公司的尾板卷深加工为实际背景,分别在独立最优、联合最优和主从对策三种条件下进行了仿真计算。仿真结果表明了主从对策的供应链协调机制的有效性。     

惩罚机制下农产品质量安全投入演化博弈分析

针对农产品质量安全问题频发和消费者对优质绿色农产品有支付能力的情景，以及农产品供应链成员质量安全投入存在正外部性问题。根据农产品供应链中供应商和生产商不同行为策略的支付矩阵，构建了供应商和生产商质量安全投入的演化博弈模型，并对模型各个参数进行求解分析。最后，进行了算例分析。结果表明：农产品供应商和生产商的质量安全投入策略与双方质量安全投入的成本收益转化率密切相关，系统演化均衡随着双方质量投入成本收益转化率而不断变化。针对农产品供应链质量投入中存在"搭便车"问题，政府惩罚力度达到某一阈值才能促使供应商和生产商同时进行质量安全投入。研究结果对政府惩罚策略的制定和供应链成员质量安全投入具有一定的启示。     

责任供应链中的采购与市场定价策略决策北大核心CSSCI

针对由一个履行社会责任的供应商,另一个存在违背社会责任风险的供应商,单生产商和两类顾客组成的供应链模型,考虑单源采购和不同顾客支付意愿的异质性,研究生产商的采购决策、目标市场选择以及定价策略决策。研究发现:在责任供应链中,生产商的采购决策与顾客支付意愿最大值及采购成本差异有关,而目标市场和定价策略的决策仅与顾客支付意愿最大值有关;当顾客支付意愿最大值越大,生产商偏向于责任采购;当供应商之间的采购成本差异越大时,生产商偏向于非责任采购;在责任采购模式下,当顾客支付意愿最大值较小时,大众市场下的价格歧视策略为优势策略;当顾客支付意愿最大值较大时,大众市场下的统一定价策略为优势策略。     

基于JIT和VMI两种物流模式的思考与改进

本文在分析当前库存管理情况的基础上,探讨了对供应商管理用户库存模式进行优化的策略,以及在这种策略下,生产商在生产上应该采取怎样的方式。     

不同主导权位置情况下零售商双渠道策略的绩效对比研究

当前传统零售商纷纷发展在线销售渠道并广泛采用供应商代发货的经营模式,这进一步增强了零售商的终端优势。以家电和快速消费品为代表的行业中,零售商正在逐步从生产商手中夺取主导权,零售商与供应商的关系受到供应链主导权位置的影响而变得更加复杂。本文针对这种复杂供应链现实问题,开发出包含承诺费的零售商双渠道协调机制,计算获得供应商主导和零售商主导两种不同情况下的供应链协调优化策略。通过对比供应商主导和零售商主导供应链的利润构成情况,我们发现供应链成员可以通过主导权为自己谋取更大利润;供应商主导型供应链的整体利润水平高于零售商主导型供应链。原因在于零售商使用主导权时激励供应商提高产量,又不完全确定自己的订购量,会导致供应商产生可能的缺货成本或产品过剩造成的浪费;零售商主导型供应链中供应商的产量更大。     

不同折扣券发放模式下的供应链定价与协调策略

本文研究了由生产商和零售商组成的两阶段供应链的最优折扣券发放模式及相应的产品定价、折扣券面值和折扣券有效期,并提出了供应链协调策略。通过比较分析生产商发放折扣券模式和零售商发放折扣券模式,得出在零售商发放折扣券时,生产商利润和供应链总利润都会得到较大的提高,而一定条件下零售商利润将会较生产商发放折扣券模式下有所下降。针对这种情况,论文提出了基于成本分摊的供应链协调策略,即在零售商发放折扣券的情况下,由生产商分摊部分折扣券发放成本以达到双赢的目的。研究表明,通过调整成本分摊比例可以在保证零售商利润不受损的前提下提升供应链的整体利润,最终达到供应链协调。     

基于可靠性分析的供应链的最优等待策略

本文对包含一个供应商和一个生产商的供应链提出了一个最优的等待策略。如果供应商不能提供足够的原材料或交货不及时,都会对生产商造成一定的损失。在这样的条件下,生产商可以采取两个措施:一个是等待供应商恢复到正常状态,另一个是重新寻找一个新的供应商。采取任何策略,生产商都会有成本。本文考虑的一个可供选择的方案是:若等待的时间短就等待,否则就重新选择一个供应商;若供应商在规定的时间内没有恢复到正常状态,则不再等待,并选择一个新的供应商。利用随机过程和可靠性理论的相关知识来寻找能使期望成本率最小的等待策略。最后,通过一个算例来说明该方案的实用性。     

一类供应商管理库存供应链协调策略研究

对有确定需求、有初始库存和库存短缺的一种畅销商品,建立了供应商管理库存的供应链模型.然后,分别分析分散式、集中式和VMI三种供应链模式下的库存补充数量最优解及各方收益情况,得到VMI的实施将可能造成供应商收益下降.再运用委托-代理理论分别讨论了信息对称和信息不对称时的VMI数量折扣契约设计问题.最后,给出算例说明了,此协调策略有助于VMI的实施.     

复杂装备主制造商-供应商主从合作激励协调Stackelberg模型

当前,飞机等复杂装备的研制越来越多的采用主制造商-供应商合作模式。由于复杂装备研制过程的不确定和复杂性,供应商的努力程度在很大程度上决定了产品的研制水平。针对复杂装备研制过程中主制造商与供应商之间的动态交互行为,基于供应商的努力程度,建立了主制造商为主方、供应商为从方的Stackelberg主从合作激励协调博弈模型,研究主制造商最优激励策略设计和供应商最优努力策略选择问题,并进行应用分析。研究结果表明,主制造商通过设计控制最优激励大小,进行利益冲突协调可实现主制造商利益最大化而供应商利益不受损的协调目的,并进一步诱导供应商的最优努力水平。     

供应链库存协调策略研究

研究和分析了直运型供应链通过共同补给期协调库存的策略问题。在该供应链中,单一供应商提供单一产品给面临随机需求的单一零售商。在所提出的库存协调策略条件下,供应商指定共同补给期,当零售商按供应商指定的共同补给期作为其订货周期时,供应商提供零售商一定的价格折扣。这种协调策略可以视为Stackelberg博弈。在阐述了解决该博弈问题的方法后,进行了数值实验,分析了采用这种协调策略的利益。     

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.