基于乘客异质性的高峰期公交出行均衡研究

在假设乘客对拥挤敏感程度具有异质性的基础上分析公交乘车的成本构成,并利用 Wardrop 用户分配第一准则对多起点单讫点的公交线路建立了基本均衡模型,通过数学推导,证明了在该假设下早高峰的存在性,并探索了均衡条件下不同类型的乘客间的混成特点以及分布特征． 算例结果支持了模型的结论． 这有助于加深对复杂交通行为的理解,对改进公交规划与管理具有理论指导价值．     

基于系统最优的城市公交专用道网络设计模型及算法

设置公交专用道是实现"公交优先"的重要手段,然而,专用道设置将改变不同交通方式的道路通行能力,进而影响交通网络的整体性能。本文试图提出一种基于系统最优思想的公交专用道网络设计方法,既保证出行者的利益,又能满足交通系统总费用最优的目标。首先,本文分析了公交专用道设置对公交车辆和社会车辆这两种交通方式道路通行能力的影响,基于经典的BPR函数,构造了考虑专用道设置的不同方式的路段阻抗函数。其次,分析了出行者在多方式交通网络中的模式选择和路径选择问题,采用用户平衡理论分析了城市多方式交通平衡配流问题,给出了相应的变分不等式模型。更进一步,采用双层规划方法构造了基于系统最优的城市公交专用道网络设计模型,该模型以交通网络总费用最小为优化目标,并考虑了不同交通方式的平衡流量约束,采用分支定界算法对该双层规划模型进行求解。最后,通过一个简单算例对模型及算法的可行性和有效性进行了分析和验证。     

基于财政补贴的拥挤定价下公交收费策略研究

交通拥挤是目前世界上多数大中城市普遍面临的问题,公交优先和拥挤定价是针时该问题的有效管理措施.巨额的公交财政补贴,往往是我国城市推行公交优先政策的障碍.本文采用交通行为科学的理论和方法,从系统科学的角度将财政补贴、拥挤定价和公交收费等问题结合起来,设计了基于财政补贴的拥挤定价下的公交收费策略,解释了如何通过拥挤定价和公交收费等手段实现缓解交通压力减少公交财政补贴的管理目标.本文以广州市为典型,进行了相应的策略分析.     

城市公交系统内乘客出行动态均衡模型

通过引入城市公共交通车辆内乘客的拥挤成本,建立了基于乘客的出发时间选择的动态出行均衡模型,并对具有不同运输能力的公交方式所导致的乘客出行差异进行了比较分析.研究结果表明大容量公共交通能使沿线上下游站点乘客都收益,而小容量公交车辆在高峰期会被远距离出行者优先挤占,从而有可能加大下游站点乘客的出行成本.算例结果支持了模型的结论.这有助于加深对复杂交通行为的理解,对改进公交规划与管理具有理论指导价值.     

城市道路系统多时段、多出行方式拥挤定价模型

随着城市经济的发展,交通拥挤的问题变得越来越突出,交通拥挤收费逐渐成为解决这一问题的新管理措施.本文分析多种出行方式的单向道路,在高峰和前高峰两个时间段下拥挤定价的问题.结合杭州交通拥挤现状进行实证模拟,比较各种拥挤收费定价方案,并得出各拥挤定价实施的社会效率.     

基于均值-超量系统总阻抗的随机拥挤收费模型

文章研究出行需求不确定环境下的拥挤收费问题,采用均值-超量系统总阻抗作为风险评价指标。均值-超量系统总阻抗风险指标,既能够保证系统总阻抗以一定的置信水平α小于决策者的预算,又保证当实际系统总阻抗超过决策者预算时引起的超量延误的均值最小,因此将它作为拥挤收费模型的目标函数能够更加全面地刻画不确定环境下系统总阻抗的分布特征。本文以最小化均值-超量系统总阻抗作为拥挤收费的目标,建立需求不确定条件下的拥挤收费模型。该模型能够更好地反映决策者面对不精确的出行需求数据的风险态度。通过蒙特卡洛模拟的方式将其转化为确定性的模型,降低了求解的复杂性。通过算例分析可得,与期望值模型相比,该模型具有更强的适应性。     

城市交通出行方式选择的演化博弈分析

交通出行方式的选择是交通管理者、交通用户等交通参与者之间的一个博弈过程,在用户之间的长期动态博弈过程中,交通出行方式的结构会在一定条件下达到演化稳定状态.本文假设用户是有限理性的,对交通出行方式的博弈和演化过程进行了分析,建立了单总体出行方式演化博弈模型,运用演化博弈理论导出出行方式选择的演化稳定策略,从而为交通政策的制定、交通管理策略效果的评价等提供决策支持.     

公共与个体竞争交通系统的定价研究

针对一个公共与个体两种交通方式并存的竞争系统,扩展了Tabuchi的定价与方式划分研究．扩展包括两个方面,一是考虑公共交通产生的以身体接触为主的不舒服因素．二是考虑两种交通方式在行驶时间上的差异,通过寻找出行者选择不同交通方式的成本平衡点,推导 和比较j各种交通收费政策下的流量分布和系统总成拳,进一步加深j对竞争系统定价和方式划分问题的认识．且讨论了一个颇有吸引力的收费补贴政策,即合理地从个体交通出行者身 上收费,来贴补可能亏损的公共交通系统．     

重庆轻轨时代市民出行方式改变研究

随着社会经济的发展及城市交通基础设施建设的完善,城市居民出行选择的交通方式日趋多样化。本文主要对重庆市城市交通设施的逐步完善及4条轨道交通线路的建成运行,对建设前后重庆市市民日常出行方式进行了调查研究,以期规划市民出行时应选择的合理交通工具,缓解重庆市交通拥堵现状。研究结果表明,出行方式的多元化日趋明显,轻轨成为更多人出行的选择,公交的选择率稍逊于轻轨但仍然深受人们青睐。     

高峰期内公交车均衡乘车行为与制度安排

研究早晨高峰期内出行者由郊区住处乘公交车到达市中心工作地的交通行为,所建立的均衡乘车行为模型考虑了时间延误成本和车内拥挤成本,得到了固定需求下的最优发车间隔.在弹性需求下,比较了系统最优、垄断和寡头竞争三种不同制度安排下所导致的公交票价、公交车班次数、公司利润和社会净收益等指标.     

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.     

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.     

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.     

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.