Solving the Economic Lot-Scheduling Problem Using the Method of Prime Subperiods

In recent years the reported successes of Japanese production systems, particularly the just-in-time approach to inventory control, has caused managers to focus more of their attention on efficient decision-making procedures for determining production schedules that minimize inventory costs. One such potential area of attention is the economic lot-scheduling problem (ELSP), which occurs in a variety of manufacturing environments where machining operations are prevalent. The economic lot-scheduling problem addresses the determination of lot sizes for N products with constant demand (and cycled through one machine with a given production rate) to minimize setup and inventory costs. The most successful solution approaches to the ELSP have been based on the concept of a basic period that is of sufficient length for the production of all items, even though each item might not be produced during each repetition of the basic period. This paper proposes a heuristic approach to the solution of the ELSP (referred to as the method of prime subperiods), which is an extension of the basic period approaches. The procedure is described and demonstrated via an example and then tested using a set of six example problems previously employed in the literature related to the ELSP. The results indicate as good or superior performance by the proposed method of prime subperiods.     

Approximating the Shapiro-Wilk W-test for non-normality

A new approximation for the coefficients required to calculate the Shapiro-WilkW-test is derived. It is easy to calculate and applies for any sample size greater than 3. A normalizing transformation for theW statistic is given, enabling itsP-value to be computed simply. The distribution of the new approximation toW agrees well with published critical points which use exact coefficients.     

Individual status at the start of rehabilitation: Implications for vocational rehabilitation programs

This research investigated the situation of 143 unemployed sick leavers at the start of vocational rehabilitation in Sweden. It is argued in this paper that in order to gain a meaningful picture of the vocational rehabilitation process it is necessary to know and understand something of individual differences and status at the onset. In doing so, assessment was carried out of the possible influence of one contextual factor and five individual factors on health, duration of sick leave and unemployment. Findings suggest that individual differences exist in health status, length of sick leave and unemployment, at the upstart of vocational rehabilitating. Locus of control was found to exert important influence on the differences between the individuals in the study sample, with persons of external locus of control having a less favourable point of departure at the start of vocational rehabilitation compared to other groups. It is therefore assumed that these persons will be in greater need of support during the vocational rehabilitation process. The level of unemployment within a geographical area was also found to influence the length of sick leave. CONCLUSIONS: Our suggestion is for rehabilitation programs to be developed and selected to match the special needs and differences whether they are of individual or of social nature.     

Kuznets’s Inverted U-Curve Hypothesis: The Rise,Demise, and Continued Relevance of a Socioeconomic Law

This paper provides a historical analysis of the changing significance of the most influential statement ever made on inequality and development—Simon Kuznets’s “inverted U-curve hypothesis.” The shifting interpretations and appropriations of the hypothesis over time—from its status as a speculative supposition in 1955, to its rise and fall as a reified socioeconomic law, to its contested standing in the social sciences today—demonstrate how Kuznets’s arguments, originally advanced under more limited conditions, became transformed into overarching theoretical, empirical, and political constructions. This history suggests that even empirically grounded and testable social science models are contingent on the broader social and political contexts in which they are produced and negotiated.     

Do Demographic Characteristics Make a Difference to Burnout among Hong Kong Secondary School Teachers?

This study aims to investigate the relationship between teachers demographic variables and burnout in Hong Kong using the Maslach Burnout Inventory. It is found that when compared with the North American normative data, Hong Kong teachers scored in the average range of burnout in emotional exhaustion and personal accomplishment while they scored in the low range of burnout in depersonalization. Gender differences were found in all three burnout syndromes, and teachers who were younger, unmarried, without religious beliefs, less experienced, without finishing professional training and of junior rank were more consistently burned out. Whereas age was the strongest predictor for emotional exhaustion and depersonalization, teachers rank is the best predictor for personal accomplishment. However, the effect of demographic characteristics of teachers on burnout is not that salient.     

Tools for Comparative Analysis of Alternatives: Competing or Complementary Perspectives?

A third generation of environmental policy making and risk management will increasingly impose environmental measures, which may give rise to analyzing countervailing risks. Therefore, a comprehensive analysis of all risks associated with the decision alternatives will aid decision-makers in prioritizing alternatives that effectively reduce both target and countervailing risks. Starting with the metaphor of the ripples caused by a stone that is thrown into a pond, we identify 10 types of ripples that symbolize, in our case, risks that deserve closer examination: direct, upstream, downstream, accidental risks, occupational risks, risks due to offsetting behavior, change in disposable income, macro-economic changes, depletion of natural resources, and risks to the manmade environment. Tools to analyze these risks were developed independently and recently have been applied to overlapping fields of application. This suggests that either the tools should be linked in a unified framework for comparative analysis or that the appropriate field of application for single tools should be better understood. The goals of this article are to create a better foundation for the understanding of the nature and coverage of available tools and to identify the remaining gaps. None of the tools is designed to deal with all 10 types of risk. Provided data suggest that, of the 10 types of identified risks, those associated with changes in disposable income may be particularly significant when decision alternatives differ with respect to their effects on disposable income. Finally, the present analysis was limited to analytical questions and did not capture the important role of the decision-making process itself.     

Polyhedral dynamics and conflict mobilization in social networks

A representation of social networks in terms of polyhedral dynamics is used to study the mobilization of individuals in a specific social network. By making use of the distinction between backcloth and traffic, the analysis shows there are compelling structural reasons for the outcome of the mobilization process in the particular network studied.