重型装备制造企业基于客户需求意向提前采购问题决策研究

在重型装备制造企业,一些核心部件由于采购周期较长,客户需要的交货周期较短,无法按销售订单进行采购。企业往往通过客户需求预测来实施提前采购,从而加大了企业的采购风险和库存成本。本文提出了基于客户需求意向的提前采购策略,当从销售部门获取的客户需求意向可以通过一定的概率转化为实际订单时,依据这一客户需求意向进行提前采购就是合理的选择。     

Make-to-Order 模式下多产品占线生产策略研究

本文研究的是按订单生产模式企业面对需求不确定条件下的生产决策问题.这类企业经常会遇到如下情形:客户的产品订单需求变动具有不可预期性,同时生产单批产品的固定成本较高,企业在承担一定的延期惩罚费用的条件下可以延期交货.因此需要考虑采用某种适当的生产策略来减少成本损失,即需要研究在未来产品订单需求不确定的条件下确定在什么时间对哪个产品进行生产使得总的固定生产成本及延期惩罚成本最优的决策问题.以往的研究一般都是假设包括订单到达时刻和订单需求量等需求信息是随机波动的,而实际情况中这些信息常常是不可预测且不能用概率分布刻画的.因此,本文从占线理论出发考虑了未来订单需求信息未知情形下的最优生产决策问题,构造了相应的数学模型,设计了一个竞争策略,证明了其具有较好的常数竞争比.数值分析进一步验证了该策略的有效性.     

随机订单干扰下考虑合并决策的供应链网络调度研究

为满足客户个性化需求的快速响应，企业需具备柔性的外部供应链网络结构，以协同方式共同完成产品生产。本文考虑具有交互特征的多个不同类型协同供应链网络，构建生产成本、库存成本、等待成本以及订单延期交货成本最小化的目标函数，并设计合并决策判断变量构建同类订单在相同协同企业处的开始时间约束。此外，模型中考虑确定订单以及随机订单两种类型订单，并设计随机订单在区间时间段中离散时间点的到达概率。为获取协同供应链网络生产调度优化策略，基于随机订单到达与否的场景构建四个子决策模型，并进一步设计判断提前安排随机订单协同生产和不提前安排随机订单协同生产不同调度策略下成本差异的主决策模型。仿真结果表明合并决策在带来生产成本效益的同时也引起了部分订单的延期交货，且不同类型的协同供应链网络对随机订单的抗干扰能力存在一定程度的差异。     

基于不公平厌恶或地位追求的创新顾客最优合同类型研究

本文首先从创新顾客的公平偏好程度、薪酬合同类型（最优激励系数）与激励机制效果的关系入手,引入公平偏好理论（不公平厌恶和地位追求）、相对绩效评估（RPE）和参与成本要素,构建顾客参与企业新产品开发的激励模型;其次,通过模型求解和分析,探讨分析各类薪酬合同中风险成本、不公平预期损失和激励效果之间的关系;最后,通过仿真实验验证并确定企业采用的创新顾客最优薪酬合同类型。研究发现：在同一薪酬合同下,创新顾客愈不在意其参与成本的投入,该合同的激励效果愈积极;关于创新顾客最优合同类型的选择,意味着求解一个三方面权衡,包括风险成本、不公平预期损失和公平偏好的激励效果;对于公平偏好程度较低的创新顾客,企业可采用相对绩效合同,例如锦标竞争合同;对于公平偏好程度较高的创新顾客,当其风险规避程度较高时,可采用团队报酬合同,当其风险规避程度较低时,可采用完美团队合同。     

基于顾客渠道偏好的全渠道零售商库存研究

本文以全渠道零售商门店库存为背景,以企业利润最大化为目标,从顾客渠道偏好、产品质量和顾客类型等方面分析顾客退货带来的损失对全渠道零售商门店最优库存的影响。首先分析传统线上线下模式且不考虑顾客流失的情形,然后分析存在顾客流失的情形,进而分析通过实体展厅有效降低顾客退货概率和顾客流失的情形。研究结果表明：顾客对产品的购买意愿较小时,所有顾客都到线下渠道,此时零售商需增加门店库存,减少顾客流失,增加收益,库存增加的数量与顾客的流失概率有关;开通展厅功能有效降低退货概率和顾客流失时,零售商应减少门店库存,增加企业利润;当产品质量问题引起的两个渠道退货概率都很高时,零售商是增大还是减少门店库存,与两个渠道的退货损失和存在渠道偏好顾客的概率相关。本文研究对于全渠道零售商在考虑顾客退货损失的基础上设置最合理的门店库存有一定的指导意义和实际应用价值。     

需求随机时的存货质押贷款质押率决策研究

需求波动导致的风险是存货质押融资区别于有价证券质押融资的主要方面.本文研究了当存货的需求随机波动时,银行的最优质押率决策问题,并详细分析了不同的风险偏好对质押率的影响,结论表明风险厌恶及损失规避时的质押率均低于风险中性时的质押率.本文同时还分析了当质押率影响贷款企业的库存决策时,银行的最优质押率决策.最后,通过数值算例验证了文章的结论.     

提前期、构建成本和短缺量拖后率均可控的EOQ模型

传统库存模型通常将提前期和构建成本视为不可控制。事实上可以通过追加投资缩短提前期和降低构建成本。缺货期间,为减少订单丢失量和补偿顾客的损失,供应商会给予一定的价格折扣。现实库存系统中,容易得到需求的期望值和标准差,但较难得到其分布规律。基于此,考虑短缺量拖后率与价格折扣和缺货期间库存水平相关,提出了一种需求为任意分布且提前期和构建成本均可控的EOQ模型,证明了模型存在唯一最优解,给出了一种寻优算法。数值仿真分析表明,一般情况下,压缩提前期和降低构建成本能降低订购批量和安全库存,降低库存总成本;短缺量拖后系数和缺货概率对库存总成本影响较大,企业应尽量降低缺货概率,尤其在短缺量拖后系数较小时。     

并行设计减少返工

要实现定制产品的快速交货,很重要的一点是产品设计完成之后,能够直接平滑地过渡到生产制造阶段,拿到图纸后就可以制造生产,减小由于设计不能满足生产制造要求而进行设计修改或设计返工;避免由于制造工艺技术、原材料零件等生产准备不足而延误生产。按照传统的顺序流程进行产品设计很难达到要求,必须组织制造部门的技术人员、装配人员、供应商、采购人员等共同参与产品开发,实行产品并行设计,就是在产品设计阶段尽可能同时考虑产品生命周期的所有影响因素,并及时全面评价产品设计,保证产品设计、工艺设计、制造一次成功,使产品设计与制造密切衔接,实现快速交货。     

时间窗口约束下基于改进蚁群算法的协同制造调度研究

与传统调度模式不同，协同制造模式下企业之间的调度模式极其复杂。协同企业间的加工工序路线并不固定，且不同类型产品具有不同的加工路线网络。为此本文针对平衡型、瓶颈型、跳跃型、混合型四类具有典型特点的协同制造网络G_p进行分析和设计；考虑制造企业同类产品合并加工策略，构建基于连续加工量的分段生产成本函数；通过设计合理的订单最早交货时间和最晚交货时间，对订单交货进行时间窗口约束，并在此基础上构建了由制造商生产成本W_c^m、订单等待W_s^k（Q_k， T'_k）和提前完工库存成本W_s^k（Q_k， T″_k）、延期惩罚成本构成W_l^k（Q_k， T'″_k）的目标函数。为求解该模型，创新性将蒙特卡洛思想引入蚁群算法，提高蚂蚁选择合理性，避免局部最优；同时，采用移动窗口[min， max]奖励机制，并且对信息素奖励乘以平衡系数k（N）提高奖励可信度，加快搜索速度并提高求解性能。仿真结果表明，本文构建调度模型合理，可以获得优化的调度结果；同时，本文提出的蚁群改进寻优算法具有良好的求解速度和收敛性，算法具有较好的稳定性。     

企业呆滞存货形成的原因及改善对策研究

呆滞存货管理是企业管理中的一项重要内容,尤其是在原物料及产品品种多样化的制造行业,如何预防和减少物料呆滞的产生,使呆滞损失降至最低;以及对形成的呆滞及时、有效的进行处理,以改善库存结构,提高库存周转率和资金使用效率,已成为众多制造企业库存控制与管理面临的一大课题。本文以制造企业(M公司)呆滞物料控制为研究对象,分析其存货管理的不足,找出呆滞物料产生的主要原因,分析并拟定改善对策。论文中所提到的方法对制造业提升存货管理效率、降低库存、准确掌控库存状况有一定借鉴和推广意义。     

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.     

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.     

The Danish psychosocial work environment and symptoms of stress: the main, mediating and moderating role of sense of coherence

The aim of this cross-sectional study was to explore the main, mediating and moderating role of sense of coherence (SOC) on stress symptoms and on the association between perceived psychosocial work environment and stress symptoms. The sample includes 2053 Danish employees from 52 workplaces. Hierarchical regression models were applied for each measure of stress. The results strongly supported the presence of a main effect for SOC. People with high levels of SOC experienced fewer stress symptoms. A mediating effect of SOC was also supported. Thus, SOC in part explained the association between work environment and stress symptoms. In addition, some support for a moderating effect of SOC was found, suggesting that people with higher SOC coped more efficiently with work environmental strain that people with lower SOC. Taken together the regression models explained 11-32% of the variance in stress symptoms. The results suggest that measures of individual factors such as SOC should be included in analyses of the effects of work environmental factors on stress and well-being.     

Control at work: a generalized resource factor for the prevention of musculoskeletal symptoms?

During the last two decades two potent groups of predictors for work-related musculoskeletal problems have been identified: physical work load and poor psychosocial working conditions. However, little is known about their combined effects. In this study the buffering effect of control at work with respect to the negative effects of psychological demands and physical work load on musculoskeletal problems is examined. All study variables were sampled from 431 people working in geriatric nursing homes in Germany by means of questionnaires. Main effects and interactions were tested with multiple regression analysis. The results showed that control buffered the effects of high psychological demands, but not of high physical work load; the buffering effect of control was observed only when physical work load was low. The combined effects of demands and physical work load were over-additive. Thus, the power of different predictors for musculoskeletal symptoms depended on the level of other predictors. This suggests that the efficiency of certain strategies for the prevention of musculoskeletal problems is likely to depend on the level of risk factors, with different strategies being appropriate for different levels of risk.