Solving the part families problem in discrete-parts manufacture by simulated annealing

In the production planning and control of discrete-parts manufacture, aggregation of parts into families, on the basis of similarity, is carried out to ease both long-horizon planning and short-horizon scheduling. Additional advantages are related to those of group technology (GT), such as simplifying the flow of parts and tools and reducing both set-up and production costs. The problem of formally forming part families is presented and discussed. Previous work is reviewed and assessed. Two solution approaches, one based on a location model, the other on simulated annealing, are presented and compared along with test results. The location formulation, which results in an integer programming model solved by Lagrangian relaxation, proved capable of producing solutions of excellent quality, but only for relatively small problem instances. In contrast, simulated annealing, which is a general heuristic approach to combinatorial optimization, produced solutions of comparable quality and could handle realistically large problem instances. However, careful design of the simulated annealing algorithm is crucially important. An effective design is presented.     

Family structure and child outcomes in the USA and Sweden

Previous research shows that living in a non-intact family is associated with educational disadvantages. This paper compares the relationships between childhood family structure, schooling, and earnings in Sweden and the USA. This comparison is interesting because both family structure and public policies differ significantly. We find a negative relationship between living in a non-intact family and child outcomes, and the estimates are remarkably similar in both countries. After using sibling-difference models, the correlation with family structure is no longer significant. These results cast doubt on the causal interpretation of the negative relationship between non-intact family structures and child outcomes.     

College students’ attitudes toward abortion and commitment to the issue

Male and female participants were surveyed on abortion attitudes, commitment, and abortion experience. Results revealed a normal distribution of abortion attitudes rejecting the notion that the vast majority of the sample would have significantly pro-choice views. No significant difference was found in overall abortion attitudes of males vs. females, however, individuals with direct abortion experience were found to have significantly stronger pro-choice attitudes than individuals without direct abortion experience. Overall, college students reported a moderate degree of commitment to the issue of abortion. Females were significantly more committed than males, individuals with direct abortion experience were significantly more committed than individuals without direct abortion experience, and individuals with more extreme abortion attitudes were significantly more committed than those with weaker, more ambivalent, attitudes. No significant difference was found in level of commitment between pro-choice and pro-life individuals.     

Personal income taxation under mobility, exogenous and endogenous welfare weights, and asymmetric information

This paper analyses how governments should tax labour income accruing to a group of highly skilled and geographically mobile individuals who divide their time or career between several jurisdictions. The analysis differs from previous models on migration and taxation by addressing optimal regulation when agents work for several principals. Optimal taxation is developed for social welfare functions with exogenous and endogenous welfare weights. Marginal income taxes are applied for screening purposes, and the rates are lower with endogenous than with exogenous welfare weights. Received: 22 January 1998/Accepted: 3 July 1999)     

The measurement of diversity: Ethnic and socioeconomic mixing in residential areas

Units of observation such as census tracts continue to be analyzed according to various modal characteristics while the variation or diversity existent in such units is often ignored. The qualitative or nominal-level indicators of diversity are examined which (1) are operative in the polytomous situation, and (2) measure within-unit diversity rather than divergences among units. Six qualitative indicators are explained and compared both theoretically and by example, with the Index of Qualitative Variation suggested as the most appropriate measure of diversity when variables representing a nominal scale are used. Quantitative or interval-level diversity also was examined with six measures analyzed, representing three operational situations. Because of the susceptibilities of five of the quantitative measures to skewness and variable sample sizes, the coefficient of variation was recommended for interval-level variables to evaluate within-unit diversity.     

Civil Commitment for Drug Dependency

In recent proposals for new legislation in New South Wales for dealing with drug-dependent persons, opinion has been sharply divided over the issues for and against civil commitment for drug abuse per se. This paper examines the situation as seen from a legal point of view.