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.     

Scheduling in a Management Context: Uncertain Processing Times and Non-Regular Performance Measures*

Decision makers often face scheduling problems in which processing times are not known with certainty. Non-regular performance measures, in which both earliness and tardiness are penalized, are also becoming more common in both manufacturing and service operations. We model a managerial environment with task processing times (which include sequenceindependent set-up times) prescribed by three-parameter lognormal distributions. Upon completion, each task derives a reward given by a particular piecewise-linear reward function. The objective is to select a sequence of tasks maximizing the expected total reward. The relative generality of the problem renders many enumerative methods inapplicable or computationally intractable. To overcome such difficulties we develop efficient priorityinduced construction (PIC) heuristics which build up a complete schedule by inserting tasks (singly from a list) into a partial sequence of tasks. In each partial and complete sequence a period of idle time is permitted prior to the first task. Performance on realistic-sized problems is very encouraging, with cost penalties averaging less than one percent.     

Calculation of age-specific fertility schedules from tabulations of parity in two censuses

The mathematics of stable populations recently has been generalized to cover populations with time-varying fertility and mortality by a modification incorporating the sum of age-varying growth rates in place of the fixed growth rate of a stable population. Equations that characterize nonstable populations apply to any cohort-like phenomenon with a measurable property that cumulates gains or losses through time. In particular, the equations fit the relation between a population's average parity at a given age and age-specific fertility rates previously experienced at lower ages. Techniques devised to derive an intercensal life table from single-year age distributions in two censuses are adapted to estimate accurate intercensal fertility schedules from distributions of parity by age of woman in two censuses. Birth-order specific fertility schedules are also estimated.     

Marriages of bisexual men

This study examined the marriages of 26 couples in which the husband was bisexual. The subjects were a non-clinical sample married for at least two years and intending to continue their marriages. The sample was, overall, highly educated and earned concomitantly high incomes. Subjects were administered the Klein Sexual Orientation Grid and a research questionnaire to determine successful or problematic aspects of their marriages. Subjects were, for the most part, satisfied with the quality of their marriages, sexually active within the marriages, and open about the husband's homosexual behavior. A high-level of sexual activity within the marriage, open and direct communication, a valued friendship, previous counseling or psychotherapy, cognitive flexibility, and financial independence contributed to the success of these marriages. The husbands reported a great deal of ambiguity about their homosexual behavior, and the couples reported intense conflict dealing with their open marriage styles.     

Using scenarios to develop strategies

Scenarios were not used for strategic decision-making until some time after their introduction. Structured approaches which fully use scenarios for strategy development have only emerged in the last few years. This paper describes such an approach as practised in Shell Nederland and focuses on the business environment with reference to the norms and values. A second paper dealing with the values in more details will appear in the next issue.     

Ascertaining the effect of planned organizational change on the work environment

In a dynamic environment, organizations often are required to effect major changes in operations. The success of such changes invariably depends upon numerous factors one of which is how the change affects the work environment. Therefore, in planning organizational change it is important to consider the work environment and to objectively evaluate changes in the work environment in a timely fashion so that corrective actions may be formulated if needed. Such framing and monitoring of the organizational change facilitates successful implementation of the organizational change. This paper suggests a measure which may be used in evaluating an organization's work environment. A case is discussed.     

Preschool Boys with Pervasive Hyperactivity: Early Peer Functioning and Mother–Child Relationship Influences

This study compared the peer functioning of a community sample of preschool boys with pervasive hyperactivity (N=33) and comparison boys (N=34), and examined the extent to which any differences in peer functioning between these groups could be explained by comorbid child conduct problems and parenting factors. The quality of boys’ peer relations was assessed on the basis of teacher and observer ratings of peer‐related behavior at preschool. The quality of parenting and boys’ behavior at home were assessed using the Parental Account of Children's Symptoms Interview, the Parenting Scale, and videotaped mother–son interactions. Boys with hyperactive behavior problems showed higher rates of aggressive, noncompliant, and nonsocial behaviors, and lower rates of prosocial behavior and peer acceptance than boys in the comparison group. These between‐group differences in social functioning remained significant following statistical control for the effects of conduct problems, highlighting the wide range of peer difficulties associated with preschool hyperactivity. Results of further analyses suggest that the quality of early mother–child interactions and the behavioral features of hyperactivity may make unique contributions to the 00development of peer relationship difficulties in preschool children with pervasive hyperactivity.     

What is Peace Psychology the Psychology of?

Peace psychology emerged as a distinct area of research and practice during the Cold War, when the preeminent concern was the prevention of nuclear war. Now global in scope, the focal concerns of peace psychologists are nuanced by geohistorical contexts and the distinction between episodic violence and structural violence, the latter of which also kills people, albeit slowly through the deprivation of basic need satisfaction. Accordingly, the focal concerns of contributors to this issue vary depending on geohistorical context: some being primarily concerned with patterns of behavior and cognition involved in the prevention of violent episodes and others with the amelioration of structural violence. A systems perspective is used as a framework for integrating episodes and structures of violence and peace. Articles emphasizing "systemic violence" demonstrate the interplay between structures and episodes of violence. Articles on "systemic peacebuilding" examine intergroup contact, the nonviolent management of conflict, and movement toward socially just structures, thereby yielding an increase in cooperative and equitable relationships across levels, from interpersonal to intergroup.     

Daily Variation in Adolescents' Sleep,Activities, and Psychological Well‐Being

The daily diary method was used to examine the daily dynamics of adolescent sleep time, activities, and psychological well‐being among an ethnically diverse sample of over 750 adolescents approximately 14–15 years of age. Studying and stressful demands during the day were modestly but consistently associated with less sleep that evening. Receiving less sleep at night, in turn, was modestly but consistently related to higher levels of anxiety, depressive feelings, and fatigue during the following day. In addition, the daily variability in adolescents' sleep time was notable and just as important for the youths' average levels of daily psychological well‐being as was the average amount of time spent sleeping each night. A small number of ethnic and gender differences emerged in the dynamics of adolescent sleep, activities, and well‐being. Discussion focuses on the importance of examining variability in adolescents' sleep behaviors in order to better understand the implications of sleep for adolescent well‐being and development.