A SIMULATION ANALYSIS OF THE JAPANESE JUST-IN-TIME TECHNIQUE (WITH KANBANS) FOR A MULTILINE,MULTISTAGE PRODUCTION SYSTEM

The Japanese “just-in-time with kanban” technique reduces in-process inventory to absolute minimal levels, in concert with the Japanese belief that inventory is an unnecessary evil. Due to the success of Japanese firms that employ this type of system, American firms would like to import this technique and emulate Japanese successes. But this Japanese success may be attributable not only to the just-in-time with kanban technique but also to the production environment in which the technique is employed. This paper simulates the just-in-time with kanban technique for a multiline, multistage production system in order to determine its adaptability to an American production environment that might include such characteristics as variable processing times, variable master production scheduling, and imbalances between production stages. The results have practical implications for those firms considering adoption of the Japanese technique.     

Assembly Line Balancing Using Genetic Algorithms with Heuristic-Generated Initial Populations and Multiple Evaluation Criteria*

We use genetic algorithms (GA) to solve the assembly line balancing (ALB) problem. Inparticular, we show how this technique can be used to generate feasible line balances, improve upon solutions obtained by other heuristics reported in the literature, and utilizeany one or more evaluation criteria that can be expressed in functional form. The procedure is demonstrated with two examples: (1) intimating the improvement of heuristic-generated ALB solutions by including them in the GA initial population, and (2) the possibility of balancing assembly lines with multiple criteria and side constraints. These examples suggest that GA can be a powerful tool in ALB. To investigate the utility of GA on single-criterion problems, an experiment is conducted that compares both the GA approach and conventional heuristics. Results indicate that the GA solutions are significantly improved over the heuristic solutions under the conditions studied. It is also found that the presence of heuristic-generated conventional solutions in the GA initial population leads to statistically preferred results.     

Net migration and migration effectiveness: A comparison between Australia and the United Kingdom, 1976–96

This paper explores the impact of net migration in Australia and the United Kingdom using measures of migration effectiveness computed from period-age migration data for four consecutive five-year periods. Results reported in Part 1 of this paper (Stillwellet al. 2000) suggest that while the overall effectiveness of net migration at the scale of city regions has declined over the twenty-year period in both countries, important geographical variations are evident. Part 2 considers how patterns of migration effectiveness vary by age and presents a single classification of all the city regions on the basis of age-specific effectiveness. More detailed analysis includes spatial patterns for particular age groups and net migration profiles of selected regions. Cohort effects are shown to be important for explaining changes between time periods in these regions.     

Orphanhood and Completion of Compulsory School Education Among Young People in South Africa: Findings From a National Representative Survey

We examined the association of orphanhood and completion of compulsory school education among young people in South Africa. In South Africa, school attendance is compulsory through grade 9, which should be completed before age 16. However, family and social factors such as orphanhood and poverty can hinder educational attainment. Participants were 10,452 16–24‐year‐olds who completed a South African national representative household survey. Overall, 23% had not completed compulsory school levels. In univariate analyses, school completion was lower among those who had experienced orphanhood during school‐age years, males, and those who reported household poverty. In multivariate analyses controlling for household poverty, females who had experienced maternal or paternal orphanhood were less likely to have completed school; orphanhood was not independently associated with males' school completion. Findings highlight the need for evidence‐informed policies to address the education and social welfare needs of orphans and vulnerable youth, particularly females, in South Africa.     

EFFECTS ON THE PRIMARY CAREGIVER WHEN A FAMILY MEMBER EXPERIENCES ACQUIRED BRAIN INJURY

This pilot study examines a random sample of 20 families with adults who have experienced acquired brain injury. Information about family structure pre and post accident is obtained by structured and open ended interview along with identification of the role of the primary caregiver. Analysis of the role of primary caregiver demonstrates the importance of the role of mothers and wives and the extent to which greatly increased responsibilities are acquired post accident. These increased responsibilities are a burden and alter the women's lifestyle such that their quality of life, like that of the person with brain injury, is severely impaired. This is a distinct but often unheralded outcome of acquired brain injury.     

A framework for progressively improving small area population estimates

Summary.  The paper presents a framework for small area population estimation that enables users to select a method that is fit for the purpose. The adjustments to input data that are needed before use are outlined, with emphasis on developing consistent time series of inputs. We show how geographical harmonization of small areas, which is crucial to comparisons over time, can be achieved. For two study regions, the East of England and Yorkshire and the Humber, the differences in output and consequences of adopting different methods are illustrated. The paper concludes with a discussion of how data, on stream since 1998, might be included in future small area estimates.     

Internal Migration and Urban Change in Poland

The paper investigates population change and migration over the period 1984–1994 for communes. There are important conclusions emerging from this study. The first is that we are watching now a profound change of population redistribution patterns in Poland. We observed that direct upwards hierarchical mobility has been markedly modified. The first modification is the substantial reduction of migration from rural to urban locations. There were important changes in the role of cities and towns. Largest cities, massive gainers of the seventies and eighties, have tended to lose population in the mid-nineties. It is likely that they lose population mainly to the neighbouring communes. We believe that a suburbanization process has been put into motion. Medium to large sized towns and cities, in the range between 50,000 and 500,000 as well as small, but not the smallest, towns attract substantial parts of the migration pool.