Assessment of modal effects in local area networks

Differential mode attenuation in LANs with ring and tree topologies consisting of biconical couplers and connectors or splices is assessed by the mode transition matrix method. Comparing the results to simple addition of manufacturers' data for restricted launch demonstrates that deviations in a concatenation of up to four 6 dB couplers are tolerable, if component tolerances are small.     

The Netherlands and Florida: Two Growth Management Strategies

Planning in Europe and the United States uses very different points of departure to address similar spatial goals. More specifically, the strategies employed to curb or prevent urban sprawl by the Netherlands and Florida, both considered in their respective contexts to have highly developed planning systems, are very different. In order to compare the planning systems of the two states, this study employs the concept of 'planning doctrine' as a base of analysis. The concept sheds light on the composition, character, potentials and shortcomings of both systems. Moreover, it provides a framework by which to assess the development of planning style in both systems.     

A swift Quantitative Microbiological Risk Assessment (sQMRA) tool

Classical full-scale QMRA is a valuable method to assess the effects of control measures on the public health risk of a pathogen–food product combination. However, development of these QMRA models is time consuming, data needs are substantial and it requires extensive modeling expertise. We therefore developed a simplified QMRA model especially aimed at comparing the risk of pathogen–food product combinations. The swift Quantitative Microbiological Risk Assessment (sQMRA) – tool is implemented in Microsoft Excel. Special attention is given to make the sQMRA tool insightful, for educational purposes. Like in full-scale QMRA, pathogen numbers are followed through the food chain, which in this case starts at retail and ends with the number of human cases of illness. The model is deterministic and includes cross-contamination and preparation (heating) in the kitchen and a dose–response relationship. The general setup of the sQMRA tool consists of consecutive questions for values of each of the 11 parameters, always followed by intermediate model output broken down into categories of contamination, cross-contamination and preparation. In a separate sheet, model input and output are summarized and exposure as well as cases are attributed to the distinguished categories. As a relative risk measure, intermediate and final model outputs are always compared with results from a full-scale QMRA of Campylobacter on chicken fillet. Example calculations with the sQMRA-tool were done for all combinations of Campylobacter spp. and Salmonella spp. with chicken fillet, filet americain (raw minced beef with mayonnaise) and table eggs. Data availability appeared to be partly poor. The predicted risk was highest for Salmonella spp. in table eggs and Campylobacter spp. in chicken fillet. Results indicate that the sQMRA-tool is useful for quickly obtaining relative risk estimates of pathogen–food combinations. It can thus serve as a guide for selection of combinations for applying full-scale QMRA, or for risk management – by facilitating the translation of the results of trend analysis or of a specific research project into terms of risk.     

A novel scraped cooled wall crystallizer: Recovery of sodium carbonate and ice from an industrial aqueous solution by eutectic freeze crystallization

A novel scraped cooled wall crystallizer (SCWC-2) with 130 l capacity and total heat transfer area of 2.94 m² m⁻³ crystallizer volume was specifically designed for eutectic freeze crystallization (EFC). It has been successfully tested for the recovery of Na₂CO₃ from an industrial solution. Compared with earlier designs this new crystallizer shows a high improvement in gravitational separation and ice scaling removal. High heat transfer fluxes between the heat exchanger and the solution (up to 10.5 kW m⁻²) were obtained and as a consequence high production rates were achieved.     

The Ruhrverband sewage sludge disposal concept in the conflict between European and German standards and regulations.

The Ruhrverband, acting as a water association responsible for integrated water resources management within the entire natural river basin of the Ruhr, operates a network of 83 wastewater treatment plants (WWTPs) and connected sludge disposal facilities. According to German regulations, the disposal of sewage sludge containing more than 5% of organic dry solids will be prohibited as of 1 June 2005. In Germany, the only future alternative to incineration will be the agricultural utilization of sludge. However, this way of sludge disposal is presently the subject of critical discussions in Germany because of the organic and inorganic toxic substances, which may be contained in sewage sludge, despite the fact that very stringent standards are to be met by agricultural uses. On the other hand, application of sewage sludge to agricultural land is explicitly supported by the European Sewage Sludge Directive 86/278/EEC. In the face of this controversial situation the Ruhrverband has initiated, in 2000, the development of a comprehensive and sustainable sludge and waste disposal concept for all wastewater facilities it operates in the entire Ruhr River Basin. The concept includes de-central sludge digestion and dewatering and subsequent transport to two central sludge incineration plants. It is expected that in future not more than 5% of all sludges produced in Ruhrverband's WWTPs will be used in agriculture. That means, the major part of 95% will have to be incinerated.     

Cost‐effectiveness of ergonomic interventions in production

Early cost–benefit analysis of ergonomic interventions in manufacturing is in the interest of the production management and the ergonomics specialist. Because of the variety of factors and the complexity to quantify these factors, this task is not an easy one. In this article we present a case study that illustrates that the economic benefits of ergonomics may easily overwhelm the costs because of the gain in productivity and quality, not to the economic gain associated with improved health. Finally, we propose a decision tool that addresses the relevant factors in the cost–benefit analysis of ergonomics. It gives Internet support to company managers and human factor specialists to make an economic analysis prior to the start of an ergonomic intervention project. © 2010 Wiley Periodicals, Inc.     

Sustaining complementor engagement in digital platform ecosystems: Antecedents,behaviours and engagement trajectories

Digital platform ecosystems increasingly dominate the enterprise software domain, and the persistence of platforms depends on the sustained engagement of complementors. However, there is a limited understanding of its antecedents, complementors' evaluation of antecedents and the manifestations and dynamic changes of complementors' engagement. Therefore, we investigate complementors' engagement within platform ecosystems over time. We draw on actor and stakeholder engagement from service research to conceptualise complementor engagement (CE) and create an integrated empirical understanding of CE and its dynamics in digital platform ecosystems. Our embedded case study builds on 30 interviews with complementors in Anubis and Osiris enterprise software platform ecosystems. Inductive data analysis reveals five CE antecedents: platform resources and rules, platform value proposition, platform agents, customer needs and other complementors' value propositions. The antecedents are associated with three CE behaviours: generating, networking and synchronising. Further analysis of CE over time resulted in 26 different sequences representing stable and changing engagement trajectories, the latter comprising selective, growing and abating engagement as subcategories. We show how complementors' evaluations of antecedents lead to behaviour changes, providing a novel perspective on the dynamics underlying CE. Finally, we link complementors' evaluation outcomes to their (dis)satisfaction, contributing to the discussion on what drives and impedes CE. The findings implicate the debate on dynamic platform governance and inform platform owners about using cooperative and competitive approaches in the short and long term.     

The effects of transparency on trust in and acceptance of a content-based art recommender

The increasing availability of (digital) cultural heritage artefacts offers great potential for increased access to art content, but also necessitates tools to help users deal with such abundance of information. User-adaptive art recommender systems aim to present their users with art content tailored to their interests. These systems try to adapt to the user based on feedback from the user on which artworks he or she finds interesting. Users need to be able to depend on the system to competently adapt to their feedback and find the artworks that are most interesting to them. This paper investigates the influence of transparency on user trust in and acceptance of content-based recommender systems. A between-subject experiment (N = 60) evaluated interaction with three versions of a content-based art recommender in the cultural heritage domain. This recommender system provides users with artworks that are of interest to them, based on their ratings of other artworks. Version 1 was not transparent, version 2 explained to the user why a recommendation had been made and version 3 showed a rating of how certain the system was that a recommendation would be of interest to the user. Results show that explaining to the user why a recommendation was made increased acceptance of the recommendations. Trust in the system itself was not improved by transparency. Showing how certain the system was of a recommendation did not influence trust and acceptance. A number of guidelines for design of recommender systems in the cultural heritage domain have been derived from the study’s results.

Relating conversational expressiveness to social presence and acceptance of an assistive social robot

Exploring the relationship between social presence, conversational expressiveness, and robot acceptance, we set up an experiment with a robot in an eldercare institution, comparing a more and less social condition. Participants showed more expressiveness with a more social agent and a higher score on expressiveness correlated with higher scores on social presence. Furthermore, scores on social presence correlated with the scores on the intention to use the system in the near future. However, we found no correlation between conversational expressiveness and robot acceptance.