Feinstaubemissionen trockenlaufender Friktionssysteme in Fahrzeugen

Forschung im Ingenieurwesen - Nicht nur der Verbrennungsmotor eines Fahrzeuges emittiert Feinstaub, auch durch das Bremsen und Abrollen des Reifens entstehen solche gesundheitsschädlichen...     

Getriebefedern für einen effizienten und regelbaren Betrieb von Kupplungs- und Bremssystemen in E-Fahrzeugen

Forschung im Ingenieurwesen - Nasslaufende Lamellenkupplungen und Bremsen bieten in elektrischen Antrieben als Schaltelement für ein Mehrganggetriebe oder als Bremse bei radnahen Antrieben...     

Polyether Cyclization Cascade Alterations in Response to Monensin Polyketide Synthase Mutations

The targeted manipulation of polyketide synthases has in recent years led to numerous new-to-nature polyketides. For type I polyketide synthases the response of post-polyketide synthases (PKS) processing enzymes onto the most frequently polyketide backbone manipulations is so far insufficiently studied. In particular, complex processes such as the polyether cyclisation in the biosynthesis of ionophores such as monensin pose interesting objects of research. We present here a study of the substrate promiscuity of the polyether cyclisation cascade enzymes in monensin biosynthesis in the conversion of redox derivatives of the nascent polyketide chain. LC-HRMS/MS²-based studies revealed a remarkable flexibility of the post-PKS enzymes. They acted on derivatized polyketide backbones based on the three possible polyketide redox states within two different modules and gave rise to an altered polyether structure. One of these monensin derivatives was isolated and characterized by 2D-NMR spectroscopy, crystallography, and bioactivity studies.     

Catching up or falling behind? Promising changes and persistent patterns across cohorts of economics PhDs in German-speaking countries from 1991 to 2008

We investigate economics PhDs minted at German, Austrian, and Swiss universities from 1991 to 2008. We find that cohort sizes increased overall, and the share of PhDs who publish in a peer-reviewed journal within 6 years after graduation increased from 18% in 1991 to 46% in 2008. Publishing rates are heterogeneous across departments. Younger cohorts publish slightly more compared to older cohorts, but these publications are not significantly better in terms of quality. Publication productivity is highly skewed within and between departments. A key difference between PhDs of the German-speaking area and North America lies in their patterns of collaboration.     

Synthesis of Mg2FeD6 under low pressure conditions for Mg2FeH6 hydrogen storage studies

Mg₂FeD₆ is successfully synthesised with various degrees of purity using reactive ball milling and annealing under low pressure deuterium conditions to a maximum of 10 bar. The deuteride of the low cost ternary metal hydride Mg₂FeH₆, is synthesised to enable further characterisation studies such as isotopic exchange behaviour. Both on laboratory and industrial scales, keeping the pressure low reduces the need for expensive compression systems and also minimises the quantity of gas necessary for use; therefore it is important to assess synthesis under these cost effective conditions. This is especially the case when using a specialised gas such as high purity deuterium. The maximum pressure chosen is 10 bar, to comply with the High Pressure Safety Act in Japan. This Safety Act limits the use of any gas including hydrogen and deuterium to 10 bar eliminating the use of traditional synthesis methods for Mg₂FeH₆ or Mg₂FeD₆ synthesis at high pressure (120 bar). Ball milling parameters such as milling times, ball to powder ratios as well as sintering times were altered to achieve improved Mg₂FeD₆ yields under these low pressure conditions.     

Enrichment of xanthohumol in the brewing process

Xanthohumol (XN), a component of hops, is lost in significant quantities in the conventional brewing process. In commercial beers less than 0.2 mg XN/L are found. In order to increase the yield of XN in the brewing process, the parameters of XN recovery were studied. During wort boiling, XN is largely isomerised to isoxanthohumol. Further losses are owing to the precipitation and absorption of XN to yeast cells and haze particles and by filtration. The use of XN-enriched hop products combined with a late hop dosage during wort boiling proved to be effective in increasing the XN content in beer. The yield was further raised by a low-pitching rate and the abnegation of beer stabilisation. The use of dark malts had a positive effect on the XN recovery. Investigations of roasted malt extracts revealed several high-molecular substances that are able to form complexes with XN. These complexes proved to be stable in the brewing process. Depending on the addition of roasted malt or special XN-enriched roasted malt extracts, dark beers with more than 10 mg XN/L were achieved. Results obtained led to a brewing technology that produced on an industrial scale pale wheat beer with more than 1 mg XN/L.     

Trustworthy clients: Extending TNC to web-based environments

In Trusted Network Connect (TNC), a network access decision is based on the security state of an access requesting party. This mechanism is limited to closed environments such as LANs and VPNs. In this paper, we propose solutions based on authentication standards for enabling TNC in open, web-based scenarios. In particular, an architectural model for TNC is proposed that takes additional security and privacy requirements into account. Furthermore, a communication scheme is proposed that is based on standardised protocols and message formats. This approach provides assurance as to the security state of clients accessing security sensitive web-based services.     

Editing Object Behaviour in Video Sequences

While there are various commercial-strength editing tools available today for still images, object-based manipulation of real-world video footage is still a challenging problem. In this system paper, we present a framework for interactive video editing. Our focus is on footage from a single, conventional video camera. By relying on spatio-temporal editing techniques operating on the video cube, we do not need to recover 3D scene geometry. Our framework is capable of removing and inserting objects, object motion editing, non-rigid object deformations, keyframe interpolation, as well as emulating camera motion. We demonstrate how movie shots with moderate complexity can be persuasively modified during post-processing.     

Alternating-time stream logic for multi-agent systems

Constraint automata have been introduced to provide a uniform operational model for specifying service interfaces of components, the network that yields the glue code for the components, and the operational behavior of the composite system. Constraint automata have been used as the basis for equivalence checking and model checking temporal logical properties. This paper presents a multi-player semantics for constraint automata which serves to reason about controllability, interaction and cooperation facilities of individual components or coalitions of components in a given network. We introduce a temporal logic framework, called alternating-time stream logic, that combines classical features of alternating-time logic (ATL) for concurrent games with special operators for specifying regular conditions on the data streams in the network and on the write and read operations at the I/O-ports of the components. Since constraint automata support any kind of synchronous and asynchronous peer-to-peer communication, the resulting game structure is non-standard and requires a series of nontrivial adaptations to the semantics and verification algorithms for classical alternating-time approaches.     

A new advanced experimental setup for in-depth study of the interfacial reaction during reactive wetting

Reactive wetting plays a crucial role in many technical processes, from soldering in microelectronics, production of metal/ceramic composites, to hot dip galvanizing in mass production of zinc coated steel sheet. In all these cases the wetting behavior of metal melts on different surfaces plays a crucial role in material joining and coating. In all these processes the formation of the interfacial reaction layer has to occur within as short a time as possible in order to ensure a fast overall production speed. As the interfacial layer determines the stability of the formed composites, detailed knowledge of its growth mechanisms is required for a directed process optimization. However, the investigation of the processes occurring at the buried interface between substrate and wetting phase is difficult, especially for the case of liquid metal wetting metallic or ceramic solid substrates at high temperatures. Here, a novel advanced technique for the investigation of high temperature wetting processes up to a temperature of 1100 K is presented. It is based on the sessile drop technique but, in addition, allows spinning off the droplet at any chosen wetting time, thus providing direct access to the interfacial reaction layer. Since the experimental setup is integrated into a UHV compatible reaction chamber, not only excellent control of the composition of the atmosphere is ensured, but also direct transfer to surface analytical tools such as scanning electron microscope or electron spectroscopy for chemical analysis without intermediate exposure to air is realized. As will be shown for the case of hot dip galvanising of steel, this is an outstanding advance compared to existing methods.