Redundant configuration of automated flow lines based on “Industry 4.0”-technologies

Over the past decades, robots have been heavily used for flow lines to increase productivity and product quality and to relieve workers of repetitive and dangerous tasks. However, despite continuous improvement of robots, the occurrence of failures remains a significant challenge in the operation of automated flow lines. Due to the connection of the stations in a flow line via a material handling system, failures at one station can quickly lead to throughput losses due to blocking and starving of upstream and downstream stations, respectively. To some extent, these throughput losses can be reduced by installing buffers between the stations. However, the installation of buffers requires considerable investments and scarce factory space. Therefore, the minimization of the total number of buffers is one of the primary objectives in flow line planning. Due to the advances of manufacturing technologies that form the foundation of “Industry 4.0”, new solutions to reduce throughput losses caused by equipment failures open up. One solution is a redundant configuration, in which downstream stations automatically take over the operations of failed stations in the event of failure. The throughput loss in these situations mainly depends on the level of redundancy designed into the system. Based on existing methods for the design of automated flow lines, we present two line balancing formulations for the configuration of automated flow lines under consideration of redundancies. The first formulation aims at maximizing the lines’ level of redundancy. The second formulation aims at a balanced allocation of redundancies along the line. To evaluate the presented formulations, we compare the performance with an existing line balancing approach for automated lines. With respect to this approach, improvements of the throughput rate between 3 % and 7 % are achieved.     

Linking maternal psychopathology to children's excessive crying and sleeping problems in a large representative German sample—The mediating role of social isolation and bonding difficulties

Attaining self-regulation is a major developmental task in infancy, in which many children show transient difficulties. Persistent, clinically relevant difficulties in self-regulation include excessive crying or sleeping disorders. Many families with affected children are burdened with multiple psychosocial risk. This suggests that regulatory problems are best conceptualized as the maladaptive interplay of overly burdened parents and a dysfunctional parent–child interaction. The current study examines whether social isolation and bonding difficulties function as mediating mechanisms linking maternal psychopathology to (1) children's excessive crying and (2) sleeping problems. The sample comprised N = 6598 mothers (M = 31.51 years) of children between zero to three years of age (M = 14.08 months, 50.1% girls). In addition to socio demographic data, the written questionnaire included information on maternal depression/anxiety, isolation, bonding, and children's regulatory problems. Hypotheses were tested with a mediation model controlling for psychosocial risk and child characteristics. As expected, maternal symptoms of depression/anxiety were linked to infants‘ excessive crying and sleeping problems. Social isolation and bonding difficulties mediated this association for excessive crying as well as for sleeping problems, but social isolation was a single mediator for sleeping problems only. The findings provide important insights in the mediating pathways linking maternal psychopathology to children's regulatory problems.     

Ein Optimierungsmodell für die wöchentliche Tourenplanung unter Einbeziehung der EU-Sozialvorschriften

The Regulation (EC) No 561/2006 and the Directive 2002/15/EC concern the driving and working hours as well as breaks and rest periods of drivers in road transportation. Although the regulations have an enormous effect on vehicle routing and scheduling, only parts of them have been integrated in few solution approaches and some vehicle routing models so far. This paper starts with the presentation of the restrictions of the relevant European Community regulations. Then, a mixed integer linear programming model for the vehicle routing problem with time windows including all rules of the regulations for a planning horizon of an entire week is presented. The model is solved with CPLEX and the impact of the regulations on the resulting vehicle schedules is analyzed by means of computational experiments.     

Attitudes towards foreigners and Jews in Germany: identifying the determinants of xenophobia in a large opinion survey

The ultimate aim of opinion surveys is the provision of information on the distribution of preferences and perceptions at the individual level. Yet, eliciting this information from the data is typically difficult. This paper uses a structural model to explain the answers on a set of questions regarding the perception of foreigners and Jews by native Germans. In this model it is assumed that in addition to observable individual characteristics there exists an underlying unobserved attitude towards minorities which drives the distribution of answers by native respondents. This latent variable in turn is assumed to be influenced by a set of observable socio-economic characteristics of the individuals. In order to estimate this model it is necessary to impose strong identification restrictions. Estimation results show that education is the key correlate of the perception of foreigners and Jews in Germany.     

Religiosity and Fertility Intentions: Can the Gender Regime Explain Cross-Country Differences?

Research on the relationship between religiosity and fertility intentions revealed substantial cross-national differences. In some countries, a strong and positive effect of religiosity on fertility intentions was found, while in others, the effect was weaker or not significant, and the reasons underlying these cross-national differences are still unclear. The aim of this article is to explain these macro-level differences from the perspective of the prevailing gender regime. We argue that in countries with more traditional regimes, a stronger effect of religiosity on fertility intentions could be expected than in countries with a more egalitarian view. We make use of the first wave of the Generations and Gender Survey and incorporate data from a total of 12 European countries in our analysis. We examine the influence of gender regime according to various macro-level indicators on gender attitudes and gender equality using meta-regression analyses. We also conduct robustness checks using other indicators such as the Gender Development Index. Our results reveal that the gender regime is only able to explain these differences in certain situations, specifically those relating to the long-term fertility intentions of men.     

Rank-Optimal Weighting or “How to be Best in the OECD Better Life Index?”

We present a method of rank-optimal weighting which can be used to explore the best possible position of a subject in a ranking based on a composite indicator by means of a mathematical optimization problem. As an example, we explore the dataset of the OECD Better Life Index and compute for each country a weight vector which brings it as far up in the ranking as possible with the greatest advance of the immediate rivals. The method is able to answer the question “What is the best possible rank a country can achieve with a given set of weighted indicators?” Typically, weights in composite indicators are justified normatively and not empirically. Our approach helps to give bounds on what is achievable by such normative judgments from a purely output-oriented and strongly competitive perspective. The method can serve as a basis for exact bounds in sensitivity analysis focused on ranking positions. In the OECD Better Life Index data we find that 19 out the 36 countries in the OECD Better Life Index 2014 can be brought to the top of the ranking by specific weights. We give a table of weights for each country which brings it to its highest possible position. Many countries achieve their best rank by focusing on their strong dimensions and setting the weights of many others to zero. Although setting dimensions to zero is possible in the OECD’s online tool, this contradicts the idea of better life being multidimensional in essence. We discuss modifications of the optimization problem which could take this into account, e.g. by allowing only a minimal weight of one. Methods to find rank-optimal weights can be useful for various multidimensional datasets like the ones used to rank universities or employers.     

Income tax schedule and redistribution in direct democracies – the Swiss case

This study examines redistribution policy through personal income taxes in Swiss cantons over the period 1995–2011. In a first step, redistribution measures are estimated with the help of exhaustive administrative data. Redistribution is decomposed into average tax rate and tax progression. In a second step, we investigate the impact of direct democratic institutions and their usage on tax policy and redistribution. The results suggest that the effect of direct democracy on income tax redistribution is a multilayered process. First, the theoretical availability of direct democracy tools does not seem to have the same impact as the effective use of them. Second, fiscal referendums may – in the short term –reduce redistribution through lower tax rates and lead to less tax progression. Third, an increasing number of ballots on initiatives leads to more tax progression and more redistribution in the long run. It seems that the short-term dampening effects of fiscal referendums on redistribution may be overridden in the long run by the expansive effect of popular initiatives.     

Ideen und Interessen. Zum Verhältnis von Religion und wirtschaftlicher Entwicklung

While concentrating on the rise of modern capitalism, Weber’s seminal studies have little to say about the impact of religions on contemporary economic development. The paper comments about recent approaches to find an answer to the questions Weber left open. If one disregards a priori constructions of culturalist and rational-choice-theories, these approaches end up again in restating the circular relationship between ideas and interests showed already by Weber, albeit clearly with a higher emphasis on interests. However, the author argues that it would be premature to interpret this result simply as a confirmation of Weber’s “disenchantment” thesis. Rather, it goes back to the transformation of the economy itself into an entity that preaches “values”, proclaims “visions” and in this sense develops an affinity to religious movements. The author deepens this view by referring to Marx’ and Polanyi’s interpretation of capitalism as a system of disembedded markets. The disembedding of markets gives rise to a historically new potential of social uncertainty which the actors need to cope with, thereby developing symbolisms showing striking affinities with religious forms. Nevertheless, the analogies between capitalism and religion are limited.