Damage of bearings caused by electrical discharge currents at large drives derived from latest field research results

Bearing currents are not all the same. Under certain circumstances and special use cases classic bearing insulations are not sufficient anymore to prevent bearing currents due to the operation of frequency converters. Additional corrective measures have to be implemented to reduce the source of bearing currents the common mode current. The usage of nanocrystalline tape wound cores shows high effectiveness. As part of a big field study with more than 50 large drive trains in the primary industry, the damaging mechanics of bearing currents are examined under real conditions. Of exceptional high interest is the influence of disturbances which can hardly be simulated in the laboratory. Additional to the shielded motor cable parallel installed functional potential equalization cables applied multiple times have almost no effect in regard to reducing the bearing current. With an optimal installed functional potential equalization system more than 95 percent of the common mode current can flow back through the motor cable shield to the converter. The disturbance impact in the field can influence the voltage over the bearing that breakthroughs are favored but also reduced

Charakterisierung von Mückenbrutplätzen im Roßlauer Oberluch

Das Roßlauer Oberluch bietet mit seinen Feuchtflächen ideale Lebensräume für eine artenreiche Fauna und Flora. Auch Stechmücken finden hier gute Reproduktionsbedingungen. Auf Grund der prognostizierten Klimaerwärmung könnten sich diese Bedingungen sogar noch verbessern, denn starke Regenfälle, Überschwemmungen und hohe Temperaturen begünstigen die Fortpflanzung von Stechmücken. Neben den Faktoren, die die Entwicklung der Mücken fördern, wirken natürlich auch regulierende Mechanismen. Neben Fressfeinden spielen Nahrungskonkurrenten eine wichtige Rolle für den Bestand einer Art. Während die Fressfeinde bereits gut untersucht sind, ist über die Nahrungskonkurrenten der Mückenlarven bislang wenig bekannt. Mückenlarven filtrieren organische Partikel aus dem Wasser und beanspruchen demnach dieselben Nahrungsressourcen wie filtrierende Kleinkrebse, sodass Kleinkrebse ernstzunehmende Nahrungskonkurrenten für Mückenlarven sind. 2007 wurde im Rahmen komplexer Untersuchungen im Zusammenhang mit der Deichrückverlegung eine Studie zur Charakterisierung von Mückenbrutplätzen im Roßlauer Oberluch durchgeführt. Die Ergebnisse werden im Folgenden dargestellt

Methodische Auslegung und Erprobung von Fahrzeug-Crashstrukturen

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Seasonality in extra-pulmonary tuberculosis notifications in Germany 2004-2014- a time series analysis

Background Seasonality in tuberculosis (TB) has been found in different parts of the world, showing a peak in spring/summer and a trough in autumn/winter. The evidence is less clear which factors drive seasonality. It was our aim to identify and evaluate seasonality in the notifications of TB in Germany, additionally investigating the possible variance of seasonality by disease site, sex and age group. Methods We conducted an integer-valued time series analysis using national surveillance data. We analysed the reported monthly numbers of started treatments between 2004 and 2014 for all notified TB cases and stratified by disease site, sex and age group. Results We detected seasonality in the extra-pulmonary TB cases (N = 11,219), with peaks in late spring/summer and troughs in fall/winter. For all TB notifications together (N = 51,090) and for pulmonary TB only (N = 39,714) we did not find a distinct seasonality. Additional stratified analyses did not reveal any clear differences between age groups, the sexes, or between active and passive case finding. Conclusion We found seasonality in extra-pulmonary TB only, indicating that seasonality of disease onset might be specific to the disease site. This could point towards differences in disease progression between the different clinical disease manifestations. Sex appears not to be an important driver of seasonality, whereas the role of age remains unclear as this could not be sufficiently investigated.Peer Reviewe

Uptake and absorption of fluoranthene from spiked microplastics into the digestive gland tissues of blue mussels, Mytilus edulis L.

The present work intended to investigate the fate of contaminant-loaded microplastics if ingested by benthic filter feeder Mytilus edulis under laboratory conditions. In the course of a 7-day experiment the mussels were exposed to PVC microplastics in a size range >40 mm, in doses of 2000 particles L_1 (11.56 mg L_1). Particles were either virgin or loaded with one of four different nominal concentrations of the polycyclic aromatic hydrocarbon (PAH) fluoranthene (500, 125, 31.25 and 7.8125 mg g_1). Verification of fluoranthene concentrations on the particles provided evidence of the high absorptive capacity of PVC for this PAH, indicating that comparable particles may serve as considerable accumulation sites for high concentrations of hydrophobic contaminants in the aquatic environment. Analysis of digestive gland tissues via polarised light microscopy revealed the occurrence of particles and particle aggregates within stomach and intestines of all mussels treated with microplastics, thus making the xenobiotic bioavailable. Results of contaminant analysis in mussel tissues via equilibrium sampling point to a considerable capability of microplastics for the accumulation of hydrophobic contaminants from the environment and their potential to act as vehicles for the transport of theses contaminants into organismal tissues. of fluoranthene concentrations on the particles provided evidence of the high absorptive capacity of PVC for this PAH, indicating that comparable particles may serve as considerable accumulation sites for high concentrations of hydrophobic contaminants in the aquatic environment. Analysis of digestive gland tissues via polarised light microscopy revealed the occurrence of particles and particle aggregates within stomach and intestines of all mussels treated with microplastics, thus making the xenobiotic bioavailable. Results of contaminant analysis in mussel tissues via equilibrium sampling point to a considerable capability of microplastics for the accumulation of hydrophobic contaminants from the environment and their potential to act as vehicles for the transport of theses contaminants into organismal tissues. © 2021 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY licens

Elective Interdisciplinary Project Laboratories combined with Lectures on Demand as an innovative Teaching Method for Highly motivated Students

[EN] To join learning in interdisciplinary project teams and special lectures only offered on demand is a very effective and also an innovative teaching method for highly motivated students. This kind of teaching is characterized by very active participation by the students in the teaching process. Students exert influence on the contents in the projects and lectures during the course, professors exert influence of the scientific methods. The teaching process is consequently based on partnership of the students and the teaching staffBailleu, A.; Kröger, S.; Menge, M.; Münchow-Carus, A. (2015). Elective Interdisciplinary Project Laboratories combined with Lectures on Demand as an innovative Teaching Method for Highly motivated Students. En 1ST INTERNATIONAL CONFERENCE ON HIGHER EDUCATION ADVANCES (HEAD' 15). Editorial Universitat Politècnica de València. 304-310. https://doi.org/10.4995/HEAd15.2015.34330431

Approximate clustering of time series using compact model-based descriptions

Abstract. Clustering time series is usually limited by the fact that the length of the time series has a significantly negative influence on the runtime. On the other hand, approximative clustering applied to existing compressed representations of time series (e.g. obtained through dimensionality reduction) usually suffers from low accuracy. We propose a method for the compression of time series based on mathematical models that explore dependencies between different time series. In particular, each time series is represented by a combination of a set of specific reference time series. The cost of this representation depend only on the number of reference time series rather than on the length of the time series. We show that using only a small number of reference time series yields a rather accurate representation while reducing the storage cost and runtime of clustering algorithms significantly. Our experiments illustrate that these representations can be used to produce an approximate clustering with high accuracy and considerably reduced runtime