A heuristic algorithm for minimizing maintenance workforce level

We develop a heuristic algorithm for minimizing the workforce level required to accommodate all the maintenance jobs requested within a specific time interval. Each maintenance job has its own release and due dates as well as the required man-days, and must be scheduled in a noninterrupted time interval, i.e. without preemption. However, the duration of each job is not fixed, but to be determined within a specific range. We show that this problem can be seen as a variant of the two-dimensional bin-packing problem with some additional constraints. We develop a non-linear mixed integer programming model for the proposed problem, and employ some well-known bin-packing algorithms to develop an efficient heuristic algorithm. In order to evaluate the performance of the proposed heuristic, we present a computationally efficient scheme for getting a good lower bound for the actual minimum. The computational experiment shows that the proposed heuristic algorithm performs quite satisfactorily in practice.     

Integrated project operations and personnel scheduling with multiple labour classes

The main theme of this paper is improving project schedules by integrating the scheduling of project jobs and labour resources. An ILP model is presented of the integrated project operations and personnel scheduling problem with multiple labour categories. Traditionally, this problem is solved in two steps: first, operations are scheduled by solving the resource-constrained project scheduling problem; then, labour categories are scheduled by solving the personnel days-off scheduling problem. The proposed model combines the two stages into an integrated problem, which is solved in one step. Using 48 test problems, the two methods were compared in terms of total cost, labour cost and scheduling efficiency. The results clearly indicate that the integrated model outperforms the traditional two-step method.     

燃气轮机的传感器故障检测、分离和信息重构

介绍了两种燃气轮机的传感器故障检测、分离和信息重构的方法.第一种方法是基于主元分析的平方预测误差指标.本文同时采用了自组织映射神经网络的方法,在方法与结果上与主元分析的方法进行了对比和分析.传感器故障的检测由主元分析的平方预测误差指标和自组织映射神经网络的误差估计执行,贡献率图用来实行故障的分离,最后的信息重构由主元分析和自组织映射神经网络延伸的算法执行.实际工业燃气轮机的数据验证了两种方法的准确性和可行性.     

One country,three populations: Trust in police among migrants,villagers, and urbanites in China

While the past decade has witnessed the burgeoning of research on public assessments of the police in China, marginalized social groups have rarely been considered in this line of inquiry. Using data collected from migrant workers, rural villagers, and urban dwellers, this study assesses whether Chinese perceptions of the police are distinguishable along procedural-based trust and outcome-based trust and whether expressive concerns and instrumental concerns are predictive of trust in the police. Findings show that Chinese citizens tend to conflate procedural-based trust and outcome-based trust. Expressive concerns play a more important role than instrumental concerns, with such expressive variables as trust in neighborhood residents committee, perceived law and order, and quality of life influencing trust in the police. Public perceptions of police trustworthiness are also significantly linked to media influence. Directions for future research are discussed.     

DDMA-charts: Nonparametric multivariate moving average control charts based on data depth

Summary: This paper studies the DDMA–chart, a data depth based moving–average control chart for monitoring multivariate data. This chart is nonparametric and it can detect simultaneously location and scale changes in the process. It improves upon the existing r– and Q–chart in the efficiency of detecting location changes. Both theoretical justifications and simulation studies are provided. Comparisons with some existing multivariate control charts via simulation results are also provided. Some applications of the DDMA–chart to the analysis of airline performance data (collected by the FAA) are demonstrated. The results indicate that the DDMA–chart is an effective nonparametric multivariate control chart.*Research supported in part by grants from the National Science Foundation, the National Security Agency, and the Federal Aviation Administration. The discussion on aviation safety in this paper reects the views of the authors, who are solely responsible for the accuracy of the analysis results presented herein, and does not necessarily reect the official view or policy of the FAA. The dataset used in this paper has been partially masked in order to protect confidentiality.     

Work–family conflict: comparing the experiences of Turkish and native Belgian women

ABSTRACT

While research has focused on a number of dimensions of work–family conflict (WFC), hardly any literature exists that analyses how differences in family systems might help to explain variations in WFC experiences. By employing Reher’s typology of strong and weak family ties to integrate existing research and identify unaddressed features, this study finds that researchers have generally understudied the role of structural family ties on WFC. Qualitative data gathered from interviews with highly educated native Belgian and Turkish immigrant women living in Belgium are used to analyse variation in the WFC experiences and coping strategies of these two groups. The results suggest that a number of interconnected factors related to family systems – including internalisation of gender roles, division of family-related responsibilities, support mechanisms and external pressures from family and society, and socialisation processes of minority women in both family structures – are highly significant in explaining variations in women’s WFC experiences.     

RECYCLING IN MULTIFAMILY DWELLINGS: DOES CONVENIENCE MATTER?

Factors that decrease the time cost of recycling have significant positive correlations with recycling rates in multifamily dwellings (MFDs). Waste-management experts have previously used anecdotes to infer a link between convenience and waste-diversion rates in MFD recycling programs. This article confirms and quantifies that link by applying probit and double-censored tobit analysis to survey data from 214 households in Urbana, Illinois. We find a strong connection between recycling rates and the perceived presence of adequate interior space for processing recyclables, and distance to recycling bins affects container-recycling intensity. The results have implications for cost-effective design of MFD recycling programs.(JEL DI , Q2 )