Einlaufverhalten nasslaufender Lamellenkupplungen im Schlupfbetrieb

Forschung im Ingenieurwesen - Nasslaufende Lamellenkupplungen weisen zu Betriebsbeginn eine Phase des Einlaufens auf, in der sich das Reibungsverhalten durch Anpassung der Reibflächen...     

Effiziente CFD-Simulationen zur Berechnung des Schleppmoments nasslaufender Lamellenkupplungen im Abgleich mit Prüfstandmessungen

Forschung im Ingenieurwesen - Nasslaufende Lamellenkupplungen und -bremsen stellen eine wichtige Baugruppe von modernen lastschaltbaren Getrieben, Schlepper-Bremsen sowie...     

Spontanschädigungsverhalten von nasslaufenden Lamellenkupplungen mit organischen und metallischen Reibbelägen

Forschung im Ingenieurwesen - Ausfälle von Lamellenkupplungen sind aufgrund der oftmals sicherheitsrelevanten Funktionen, die diese in Antriebssträngen übernehmen,...     

Nanoparticle self-assembly on a DNA-scaffold written by single-molecule cut-and-paste

Self-assembly guided by molecular recognition has in the past been employed to assemble nanoparticle superstructures like hypercrystals or nanoparticle molecules. An alternative approach, the direct molecule-by-molecule assembly of nanoscale superstructures, was demonstrated recently. Here we present a hybrid approach where we first assemble a pattern of binding sites one-by-one at a surface and then allow different nanoparticles to attach by self-assembly. For this approach, biotin bearing DNA oligomers were picked up from a depot using a cDNA strand bound to an AFM tip. These units were deposited in the target area by hybridization, forming a recognition pattern on this surface. Fluorescent semiconductor nanoparticles conjugated with streptavidin were allowed to assemble on this scaffold and to form the final nanoparticle superstructures.     

Direct conversion of methane to higher hydrocarbons via an oxygen free,low-temperature route

The direct conversion of methane to higher hydrocarbons over a silica-supported Ru catalyst has been investigated via an oxygen free, two-step route. The reaction consists of decomposition of methane over a 3% silica-supp orted Ru catalyst at temperatures between 400 and 800 K to produce surface carbonaceous species followed by rehydrogenation of these species to higher hydrocarbons at of 368 K. It was found that the Ru/SiO₂ catalyst exhibits a trend similar to that for single-crystal Ru catalysts. However, the temperature at which a maximum in ethane selectivity occurs shifts toward a higher temperature. It was also found that the ethane yield can be optimized by changing the surface carbon coverage. Under optimum conditions a net ethane yield of about 13–15% has been realized. For this two-step reaction sequence, only a few reaction cycles could be operated without intermediate high temperature rehydrogenation and without significant loss in ethane yield. This is attributed to large amounts of inactive carbon that could not be hydrogenated at 368 K. Higher methane partial pressures were found to be desirable for this reaction. The activity of the catalyst could also be maintained at total pressures up to 10 atm.     

Verkürzte Lebensdauertests von Zahnradgetrieben unter Lastkollektivbeanspruchung

Forschung im Ingenieurwesen - Im Rahmen dieses Beitrags wird ein Vorgehensmodell zur Planung und Durchführung von verkürzten Lebensdauertests bei Zahnradgetrieben vorgestellt, um einen...