Applying designed experiments to optimize the performance of genetic algorithms used for scheduling complex products in the capital goods industry

Conventional optimization approaches, such as Linear Programming, Dynamic Programming and Branch-and-Bound methods are well established for solving relatively simple scheduling problems. Algorithms such as Simulated Annealing, Taboo Search and Genetic Algorithms (GA) have recently been applied to large combinatorial problems. Owing to the complex nature of these problems it is often impossible to search the whole problem space and an optimal solution cannot, therefore, be guaranteed. A BiCriteria Genetic Algorithm (BCGA) has been developed for the scheduling of complex products with multiple resource constraints and deep product structure. This GA identifies and corrects infeasible schedules and takes account of the early supply of components and assemblies, late delivery of final products and capacity utilization. The research has used manufacturing data obtained from a capital goods company. Genetic Algorithms include a number of parameters, including the probabilities of crossover and mutation, the population size and the number of generations. The BCGA scheduling tool provides 16 alternative crossover operations and eight different mutation mechanisms. The overall objective of this study was to develop an efficient design-of-experiments approach to identify genetic algorithm operators and parameters that produce solutions with minimum total cost. The case studies were based upon a complex, computationally intensive scheduling problem that was insoluble using conventional approaches. This paper describes an efficient sequential experimental strategy that enabled this work to be performed within a reasonable time. The first stage was a screening experiment, which had a fractional factorial embedded within a half Latin-square design. The second stage was a half-fraction design with a reduced number of GA operators. The results are compared with previous studies. It is demonstrated that, in this case, improved GA performance was achieved using the experimental strategy proposed. The appropriate genetic operators and parameters may be case specific, leading to the view that experimental design may be the best way to proceed when finding the 'best' combination of GA operators and parameters.     

Dignity,Wisdom, and Tomorrow's Ethical Business Leader

This article examines the role wisdom and dignity play in developing ethical business leaders, or what we call shamanic leaders, for the twenty‐first century. We define wisdom as the integration of moral imagination (the good), systems understanding (the true), and aesthetic sensibility (the beautiful) into decisions, actions, and practices in the service of a better world. Dignity is our inherent value, worth, and vulnerability, a core aspect of humanity that each of us is born with. The challenges of developing shamanic leaders, i.e., individuals who evidence the shamanic attributes of healing, connecting, and sensemaking, are discussed, including how to think about and embody wisdom, and the learning that is required to understand and lead with dignity. We argue that dignity and wisdom can be learned and provide the reader with insights into what is required to promote an inclusive and integrated culture where human flourishing and well‐being are at the core of ethical leadership.     

Sequential Neighborhood Effects: The Effect of Long-Term Exposure to Concentrated Disadvantage on Children’s Reading and Math Test Scores

Prior research has suggested that children living in a disadvantaged neighborhood have lower achievement test scores, but these studies typically have not estimated causal effects that account for neighborhood choice. Recent studies used propensity score methods to account for the endogeneity of neighborhood exposures, comparing disadvantaged and nondisadvantaged neighborhoods. We develop an alternative propensity function approach in which cumulative neighborhood effects are modeled as a continuous treatment variable. This approach offers several advantages. We use our approach to examine the cumulative effects of neighborhood disadvantage on reading and math test scores in Los Angeles. Our substantive results indicate that recency of exposure to disadvantaged neighborhoods may be more important than average exposure for children’s test scores. We conclude that studies of child development should consider both average cumulative neighborhood exposure and the timing of this exposure.     

Economic development and fertility change in Mexico, 1950–1970

This paper is an attempt to isolate the determinants of fertility in Mexico. Of the variables included, two are significant in accounting for differences in the level of completed fertility in the 32 "states" in 1970. They are the share of the labor force in agriculture, which is directly related to fertility, and the percentage of the population speaking an indigenous language, which shows an inverse relationship.The most important factors acting to reduce total fertility rates over time are increases in life expectancy and declines in the share of the labor force in agriculture. However, based on the estimated linear relationship, these two variables by themselves are not adequate to achieve a rapid decline in fertility in the future.     

Prevalence and predictors of PTSD among a college sample

Objective:This study examined the prevalence and correlates of probable posttraumatic stress disorder (PTSD) in freshman entering college and prospective associations of probable PTSD with additional outcomes. Participants: 2,310 students with data collected from Fall 2014 through Spring 2015. Methods: Incoming freshman completed a survey assessing for relevant variables at the beginning of fall semester and during the spring semester. Results: Seventy percent of the sample endorsed experiencing at least one potentially traumatic event (PTE). 34.4% of PTE exposed individuals met criteria for probable PTSD. Female sex, higher depressive and anxiety symptoms, and interpersonal PTE count were positively associated with PTSD symptoms. Higher PTSD symptoms were associated with higher anxiety and depressive symptoms, and new-onset interpersonal PTE. Conclusions: Identification of factors contributing to risk for PTSD is essential to inform prevention and intervention efforts. Intervention efforts should be targeted to students experiencing PTSD symptoms as they enter college.     

'Good lesbian, bad lesbian…': regulating heterosexuality in fostering and adoption assessments

The paper examines the assessment of lesbians who apply to foster or adopt, using data generated from 30 interviews with local authority social workers. Using feminist and queer theories, the author suggests that lesbian applicants pose a challenge to the discourse of 'compulsory gender and heterosexuality' which structures fostering and adoption work. It is argued that this discourse relies upon a series of assumptions about the automatic fitness of heterosexual applicants, especially concerning the idea of gender and sexuality role models needed for children's development. Further, this 'heteronormative' discourse relies upon the continuing need to make 'other' the categories 'lesbian' or 'gay'. The article considers how 'the lesbian' is constructed as a 'threat', as 'militant', or as 'automatically safe' in assessments, and makes the point that social work is productive of versions of the lesbian subject. The author argues that only certain versions are likely to be approved to foster or adopt, particularly that which is termed 'the good lesbian'.