A Flexible Evaluative Framework for Order Picking Systems

This paper develops a novel framework to evaluate the integral performance of order picking systems with different combinations of storage and order picking policies. The warehousing literature on order picking mostly considers minimizing either elapsed time or distance as the sole objective, whereas warehouse managers in a supply chain have to look beyond single‐dimensional performance and consider trade‐offs among different criteria. Thus managers still need a unified and efficient framework to select a portfolio of appropriate order picking policies from a multi‐criteria and contextual perspective. Our framework—combining data envelopment analysis, ranking and selection, and multiple comparisons—provides an efficient methodology to simultaneously analyze several interrelated problems in order picking systems with multiple performance attributes, such as service levels and operational costs. We demonstrate our approach through comprehensive evaluations of order picking policies in three low‐level, picker‐to‐parts rectangular warehouses facing demand variations.     

Identifying Technology Spillovers and Product Market Rivalry

The impact of R&D on growth through spillovers has been a major topic of economic research over the last thirty years. A central problem in the literature is that firm performance is affected by two countervailing “spillovers” : a positive effect from technology (knowledge) spillovers and a negative business stealing effects from product market rivals. We develop a general framework incorporating these two types of spillovers and implement this model using measures of a firm's position in technology space and productmarket space. Using panel data on U.S. firms, we show that technology spillovers quantitatively dominate, so that the gross social returns to R&D are at least twice as high as the private returns. We identify the causal effect of R&D spillovers by using changes in federal and state tax incentives for R&D. We also find that smaller firms generate lower social returns to R&D because they operate more in technological niches. Finally, we detail the desirable properties of an ideal spillover measure and how existing approaches, including our new Mahalanobis measure, compare to these criteria.     

Small sample study on estimators of life distributions and of mean survival times using randomly censored data

Whereas large-sample properties of the estimators of survival distributions using censored data have been studied by many authors, exact results for small samples have been difficult to obtain. In this paper we obtain the exact expression for the ath moment (a > 0) of the Bayes estimator of survival distribution using the censored data under proportional hazard model. Using the exact expression we compute the exact mean, variance and MSE of the Bayes estimator. Also two estimators ofthe mean survival time based on the Kaplan-Meier estimator and the Bayes estimator are compared for small samples under proportional hazards.     

Statistical Certification of Software Systems

Common software release procedures based on statistical techniques try to optimize the trade-off between further testing costs and costs due to remaining errors. We propose new software release procedures where the aim is to certify with a certain confidence level that the software does not contain errors. The underlying model is a discrete time model similar to the geometric Moranda model. The decisions are based on a mix of classical and Bayesian approaches to sequential testing and do not require any assumption on the initial number of errors.     

On the almost sure convergence for sums of negatively superadditive dependent random vectors in Hilbert spaces and its application

Abstract

This paper develops almost sure convergence for sums of negatively superadditive dependent random vectors in Hilbert spaces, we obtain Chung type SLLN and the Jaite type SLLN for sequences of negatively superadditive dependent random vectors in Hilbert spaces. Rate of convergence is studied through considering almost sure convergence to 0 of tail series. As an application, the almost sure convergence of degenerate von Mises-statistics is investigated.     

Going to work without educational qualifications: school-to-work transitions of early school leavers in Belgium

ABSTRACT

Risks of exclusion can occur in multiple forms and start early in life. Early school leavers are especially at risk of social exclusion as this is strongly related to turbulent school-to-work-transitions. These young people often find themselves in low-qualified work or unemployment. In this article, we explore the labour market experiences of early school leavers in Flanders, Belgium. In total, 15 in-depth interviews were conducted with nine early school leavers and analysed following a grounded theory approach. Our results demonstrate the difficulties early school leavers encounter in their transitions from school to work and their precarious situation in the labour market. Of particular relevance are the insights gained in revealing the perspectives of young people on the importance of educational qualifications, work experience and participation in the labour market, as well as the strategies they develop to enter the labour market without educational qualifications.     

Consensual Versus Heterogeneous Conceptions of Nationhood: The Role of Citizenship Regimes and Integration Policies Across 21 European Countries

Conceptions of nationhood (i.e., who is accepted as a member of the national ingroup) are known to be more open in countries with inclusive citizenship and integration policies. Yet, surprisingly, up to now no research has investigated whether the sharedness of these conceptions is related to national policies. Therefore, relying on data from the 2013 International Social Survey Programme, the present study examined to which extent individuals living in 188 regions of 21 European countries share similar conceptions of who is a “true” member of the nation. Both ethnic (e.g., having national ancestry) and civic (e.g., respecting national laws and institutions) criteria were considered. Multilevel analyses revealed that in countries with more inclusive policies (with inclusive citizenship regimes, and where immigrants are granted more political rights) the average regional importance granted to ethnic criteria was lower, and conceptions were more heterogeneous (i.e., less shared). Civic criteria—that are achievable—were deemed more important. This can explain the lower heterogeneity of civic conceptions of nationhood and the lack of impact of national policies (though the average regional importance of these criteria was higher where immigrants had more rights). Overall, these results suggest that inclusive as opposed to exclusive settings leave more room for differing worldviews.

     

A Network Therapy Clinic for Clients with Intellectual Disability

Over the past 30 years a systemic approach has been applied to complex cases involving intellectual disability and behaviours of concern. This paper describes a model that draws on systemic family therapy and network therapy as well as the use of a reflective team. A single session intervention was provided for families of people with intellectual disability. A systemic consultation was used as a pre‐session meeting for professionals working with the family. The systemic consultation and single session therapy allowed the family and the professional network to gain insight. Involving the professionals in the therapy session also enhanced the alliance between professionals and family. This approach assists everyone involved in the case to find a way to progress.