Master Production Scheduling Under Rolling Planning Horizons with Fixed Order Intervals

Fixed interval scheduling is studied in the context of a rolling horizon framework that is developed by building on previous work in the master scheduling area. The rolling horizon framework includes a stationary scheduling model which uses the “time fencing’concept by partitioning the planning horizon into three sections. The lengths of these sections and the frequency at which the stationary problem is updated and resolved are discussed as parameters of the rolling horizon model. Two different interpretations of the freeze interval parameter are examined, enabling confirmation and clarification of results presented in an earlier study. Details are given for three methods of calculating safety stocks as a function of rolling horizon parameters, including a method which results in optimal safety stock levels. A comparison of the safety stock methods shows that the constant safety stock method can result in inventories that are significantly above optimal under certain conditions, whereas the constant service level method consistently yields nearly optimal results.     

Constrained Forecasting: Some Implementation Guidelines

Constrained forecasting has become a popular approach to the complex task of predicting future sales. Mixed performance results have been obtained by companies employing constrained forecasting systems software packages which probably reflects the lack of any clear system implementation guidelines. A number of important operational parameters such as the number of product families, criterion used to define product families, number of system levels, etc. must be specified. This study reports on an investigation of two of these parameters: product group size and appropriate grouping criterion. Different tests are performed with the constrained forecasting system and compared to a traditional forecasting approach using product data from the Cummins Engine Company of Columbus, Indiana.     

论家庭暴力犯罪领域的两大误区

家庭暴力,尤其是其中的犯罪问题,成为近年来社会关注的焦点,但学界、立法界、司法界对这一问题长期以来在认识上存在两大误区:一是家庭暴力应加大犯罪化进程;二是对家庭暴力犯罪的处罚应与其它暴力犯罪一视同仁。论文从法律社会学、犯罪学、刑法学、伦理学、法史学等多学科的视角论证了当前我国的家庭暴力的犯罪化不宜过于宽泛,同时由于某些既定的家庭暴力犯罪重于其他暴力犯罪,故应从重处罚。     

贫困大学生心理健康教育工作浅论

本文在分析贫困大学生普遍存在的心理问题的基础上,阐述了加强大学生心理健康教育的主要内容,并积极探索通过心理健康知识宣传、心理评估、个体咨询、团体咨询等途径加大对贫困大学生的心理健康教育力度,以达到提高贫困大学生心理健康水平,促进贫困大学生健康成长的目的。     

Labor Utilization Effects of Labor Scheduling Flexibility Alternatives in a Tour Scheduling Environment

This study used a factorial experimental design and a new modeling methodology to investigate the impact of a number of labor scheduling flexibility alternatives and labor requirements characteristics on labor utilization within a tour scheduling environment. Break-placement flexibility and shift-length flexibility were found to be extremely effective in improving labor utilization for all labor requirement distributions used. Flexibility with respect to the number of days included in a tour schedule resulted in substantial improvement in labor utilization for all labor requirements distributions exhibiting daily and/or weekly variation. Surprisingly, virtually no improvement in labor utilization was achieved for any labor requirement distribution by the removal of requirements for consecutive days off. In addition, almost no improvement was found by allowing the shift start time to vary across the working days included in tours. High labor requirement amplitude was found to have a strong adverse effect on labor utilization while longer operational days were associated with improved labor utilization for all labor requirement distributions. We discuss the implications of these results for service operations management and provide suggestions for future research.     

Redesigning a Cellular Manufacturing System to Handle Long-Term Demand Changes: A Methodology and Investigation*

Cellular manufacturing systems have been proposed as an alternative to the job shop since they provide some of the operational benefits of a flow line production process, while retaining to some extent the flexibility of job shops. However, this must be balanced against the possibility of additional initial investments in equipment to form the cells and a certain loss in manufacturing flexibility, particularly in terms of the ability to deal with long-term demand changes. This paper presents a model-based heuristic cell system redesign methodology to deal with such demand changes. The methodology is validated and applied to system designs generated from several data sets published in the literature. Results show that different kinds of demand changes incur distinct kinds of costs. Further, characteristics of cell designs that can handle long-term demand changes at least cost are identified.     

The Impact of Learning and Labor Attrition on Worker Flexibility in Dual Resource Constrained Job Shops

This study investigates the impact of worker learning, worker flexibility, and labor attrition on the system performance of a dual resource constrained (DRC) job-shop. The effects of learning and labor attrition have not been previously addressed in DRC literature. Results from the study, consistent with previous literature, show that the greatest benefits are achieved when inter-departmental worker flexibility is incrementally introduced into the system. In addition, the learning environment, which depends on the initial processing time of jobs and the learning rates of workers, is shown to impact the acquisition of flexibility. The study also shows that the impact of labor attrition on system performance under certain shop conditions may be significant.     

Distinguishing Features of Just-in-Time Systems in the Make-to-Order/Assemble-to-Order Environment*

Few studies of just-in-time (JIT) implementation examine their significance in make-to-order manufacturing environments. This study examines the relative importance of several operating variables that are characteristic features of JIT systems within such environments in North America. The results suggest that the most salient features of JIT for make-to-order and assemble-to-order firms are the elimination of waste (in the form of time and defects), reduced setup time, reduced lotsize, and a smaller pool of suppliers. In addition, the results suggest that the use of non-domestic suppliers can possibly hinder efforts at JIT implementation of materials procurement.     

The effect of paid maternity leave on low-income families' welfare use in the US

Despite the critical role that paid maternity leave can assume in the economic lives of low-income families, research to date has paid insufficient attention to whether paid maternity leave reduces welfare use for low-income families. Using the Current Population Survey (CPS) March Supplement 2007–2014 with the difference-in-difference (DiD) technique, this study finds a significant policy effect of paid maternity leave on reducing the probability of using Temporary Assistance for Needy Families (TANF), TANF benefit amounts and TANF participation length. This study confirms that paid maternity leave is likely to prevent low-income families from using welfare during job interruptions stemming from the birth of a child. Given that TANF is often associated with negative political and social connotations, paid maternity leave can be used as an important social policy to improve economic security as well as offer empowerment in overall social standing for low-income mothers. The discussion focuses on the implications of the findings in a broader context of American welfare states.     

Making fathers relevant: How practitioners include both parents in talk about parenting programmes

Parenting programmes are recommended as an effective means to support parents in promoting positive relationships with, and managing the behaviour of, their children. One barrier that impedes their successful implementation is that partners, especially fathers, are less frequently recruited by child welfare services. This article reports on a study that investigated how both parents were engaged with parenting services. Direct recordings were made of initial telephone conversations between six practitioners and 28 parents referred to those services and investigated for evidence of how the other parent was recruited. Conversation analysis was used to identify how participants introduced the possibility of both parents being included in the service, how these possibilities were negotiated, and what eventual agreements were made for both parents to be included in future arrangements. Implications for practice, training, and future research are considered.