Estimation of a Change Point in a Hazard Function Based on Censored Data

The hazard function plays an important role in reliability or survival studies since it describes the instantaneous risk of failure of items at a time point, given that they have not failed before. In some real life applications, abrupt changes in the hazard function are observed due to overhauls, major operations or specific maintenance activities. In such situations it is of interest to detect the location where such a change occurs and estimate the size of the change. In this paper we consider the problem of estimating a single change point in a piecewise constant hazard function when the observed variables are subject to random censoring. We suggest an estimation procedure that is based on certain structural properties and on least squares ideas. A simulation study is carried out to compare the performance of this estimator with two estimators available in the literature: an estimator based on a functional of the Nelson-Aalen estimator and a maximum likelihood estimator. The proposed least squares estimator tums out to be less biased than the other two estimators, but has a larger variance. We illustrate the estimation method on some real data sets.     

Robustness evaluation of multisite distributed schedule with perturbed virtual jobshops

A method for evaluating the robustness of medium term multisite distributed schedule is presented. The method of robustness evaluation is based on steps and tools associated with the conceptual model of a MultiSite Reactive Production Activity Control (MSR-PAC). The MSR-PAC makes it possible to study the sensitivity of the scheduled plans in presence of perturbations. These must be evaluated before being dispatched to the shop-floors. At present, to the best of the authors' knowledge, there is no means to make this evaluation in the distributed systems such as extended enterprise. The monitoring of errors is based on the discrepancy between the two flow-shape functions that model respectively the dynamics of the scheduled manufacturing orders and the state of the perturbed production. The MSR-PAC is based on a multisite agent system and on the monitoring of the perturbed virtual jobshops. The method can also be used for controlling short term distributed production activities.     

Supply chain management: a supplier perspective

A new way of researching into supply chain management is introduced by adopting a supplier perspective. Details are given of mixed integer linear planning and simulation models. The planning model takes into consideration firm and forecast orders (customer's forecast purchasing orders) and the behaviour of the supplier's suppliers and suppliers' subcontractors. The simulation model takes into account the dynamic behaviour of the supply chain and includes the planning production behaviour of a supplying company based on the planning model. The supplier manager can use the simulation model to determine what kind of parameters most affect company performances and then propose new management rules. Quantitative results that prove the benefits of integrating forecast orders for an aeronautic supplier have been provided.     

Production and changeover control policies of a class of failure prone buffered flow-shops

This article deals with a stochastic optimal control problem for a class of buffered multi-parts flow-shops manufacturing system. The involved machines are subject to random breakdowns and repairs. The flow-shop under consideration is not completely flexible and hence requires setup time and cost in order to switch the production from a part type to another, this changeover is carried on the whole line. Our objective is to find the production plan and the sequence of setups that minimise the cost function, which penalises inventories/backlogs and setups. A continuous dynamic programming formulation of the problem is presented. Then, a numerical scheme is adopted to solve the obtained optimality conditions equations for a two buffered serial machines two parts case. A complete heuristic policy, based on the numerical observations which describe the optimal policies in system states, is developed. It will be shown that the obtained policy is a combination of a KANBAN/CONWIP and a modified hedging corridor policy. Moreover, based on our observations and existent research studies extension to cover more complex flow-shops is henceforth possible. The robustness of such a policy is illustrated through sensitivity analysis.     

Perception of Multisensory Gender Coherence in 6‐ and 9‐Month‐Old Infants

One of the most salient social categories conveyed by human faces and voices is gender. We investigated the developmental emergence of the ability to perceive the coherence of auditory and visual attributes of gender in 6‐ and 9‐month‐old infants. Infants viewed two side‐by‐side video clips of a man and a woman singing a nursery rhyme and heard a synchronous male or female sound track. Results showed that 6‐month‐old infants did not match the audible and visible attributes of gender, and 9‐month‐old infants matched only female faces and voices. These findings indicate that the ability to perceive the multisensory coherence of gender emerges relatively late in infancy and that it reflects the greater experience that most infants have with female faces and voices.     

Exploring Cultural Issues for Constellation Work in South Africa

Constellation work is a therapeutic and counselling intervention recognised in Germany and other European countries since the 1970s. Various scientists and practitioners have contributed to its theoretical and practical development, and research on the subject has increased over the past few years. However culture in constellation work has received little research attention and has not been empirically studied in African contexts. The aim of this article is to reflect on culture and its influence on constellation work in multicultural, post‐apartheid South Africa. An empirical qualitative research approach within the phenomenological paradigm was adopted. Six constellation facilitators were interviewed with in‐depth and field notes taken during participative observations of constellation workshops. The findings provide insight into culture in constellation work in the South African context. Theoretical and practical recommendations for scientists and therapy practitioners working with systemic interventions like constellation work are provided.     

Transformational leadership and optimal functioning at work: On the mediating role of employees' perceived job characteristics and motivation

This study aimed to deepen our understanding of the motivational mechanisms involved in the relationship between transformational leadership (TFL) and employee functioning. Drawing on the TFL literature, the job demands–resources model and self-determination theory, we propose an integrative model that relates TFL to employee psychological health (burnout and psychological distress), attitudes (occupational commitment and turnover intention) and performance (professional efficacy, self-reported individual and objective organizational performance) through two explanatory mechanisms: perceived job characteristics (job demands and resources) and employee motivation (autonomous and controlled). This research was conducted in two occupational settings (nurses and school principals), using a distinct variable operationalization for each. Results of both studies provide support for the hypothesized model, suggesting that TFL relates to optimal job functioning (psychological health, job attitudes and performance) by contributing to favourable perceptions of job characteristics (more resources and less demands) and high-quality work motivation (more autonomous motivation and less controlled motivation) in employees. Theoretical contributions and managerial implications as well as directions for future research are presented.     

On the psychological and motivational processes linking job characteristics to employee functioning: Insights from self-determination theory

The aim of this study was to provide insight into the differential relationships between job characteristics (job demands and resources) and employee functioning by examining the psychological and motivational processes involved. Drawing on self-determination theory, we tested a model in which job demands are positively related to negative manifestations of employee functioning (psychological distress and psychosomatic complaints) through psychological need frustration and low-quality work motivation (controlled motivation), whereas job resources are positively related to positive manifestations of employee functioning (work engagement and job performance) through need satisfaction and high-quality work motivation (autonomous motivation). Data were collected from 699 Canadian nurses. Structural equation modelling (SEM) results support the proposed model: psychological needs and work motivation partially mediated the relationship between job characteristics and employee functioning. Specifically, job demands negatively predicted employee functioning (high distress and psychosomatic complaints, low engagement and performance) through need frustration and controlled motivation. In contrast, while positively predicting need satisfaction and negatively predicting need frustration, job resources fostered optimal work motivation (more autonomous and less controlled motivation) and employee functioning. The implications for self-determination theory (SDT) and research on occupational health and stress are discussed.     

古代家训中的家庭德育思想初探

家训是古代的一种家庭伦理教科书 ,其中包含着非常丰富的家庭道德教育思想。古代家训中以德为“本”、以德为“富”、以德为“要”的家庭德育定位 ,以及倡导早期德育 ,强调道德化育的家庭德育思想 ,对于当前的独生子女家庭德育具有积极意义。     

从"为人生的艺术"到"为艺术的艺术"--周作人文学观念变迁轨迹之描述

本文通过对周作人在五四时期文学观念变化过程的描述,展示出他从主张“为人生的艺术”到转而提倡“为艺术而艺术”的复杂历程。既反映出周作人文学思想的丰富性与复杂性,也显示了五四时期相关文学概念内涵的丰富性,对我们重新认识这一时期的文学思潮及相关作家的文学思想有着重要意义。