ICES2008-1650 REDUCED FRICTION LOSSES AND WEAR BY DLC COATING OF PISTON PINS

ABSTRACT A Diamond Like Carbon (DLC) coating is well known to offer superior wear and friction behaviour. This combination of properties makes DLC suitable for many different areas of tribology. This paper concerns itself with usage in the power cylinder environment of automotive diesel engines. To estimate the potential of DLC coatings applied to piston pins in internal combustion engines, linearly reciprocating sliding wear examinations have been performed on uncoated and DLC coated component segments versus different counterpart materials as present in the power cylinder environment, including: piston (aluminium alloy), bushing (brass), piston pin (steel) and connecting rod (steel). Evaluation criteria for the tests include friction and wear performance in dry and lubricated conditions. Test results show how the DLC coatings offer impressive wear reductions for each of the different counterpart materials used. Furthermore, special emphasis is given to the analysis of the friction behaviour. As expected, the coefficient of friction (COF) decreased for aluminium and steel counterparts when the piston pin segments were DLC coated. However, for the combination of DLC with brass the COF increased in the dry condition. This surprising outcome is explained with SEM and EDX investigations of the wear traces. The tests at elevated temperature with lubrication show an inverse relationship with respect to friction criteria when compared with the dry room temperature tests for the DLC with brass combination. Examined engine tests confirm the results of the nonengine wear test rig, showing that DLC coatings applied on piston pins also exhibit properties and good potential to decrease frictional losses and fuel consumption in modern engines

Prosodic modules for speech recognition and understanding in VERBMOBIL

Within VERBMOBIL, a large project on spoken language research in Germany, two modules for detecting and recognizing prosodic events have been developed. One module operates on speech signal parameters and the word hypothesis graph, whereas the other module, designed for a novel, highly interactive architecture, only uses speech signal parameters as its input. Phrase boundaries, sentence modality, and accents are detected. The recognition rates in spontaneous dialogs are for accents up to 82,5%, for phrase boundaries up to 91,7%

Vascular Response on a Novel Fibrin-Based Coated Flow Diverter

Purpose Due to thromboembolic complications and in-stent-stenosis after flow diverter (FD) treatment, the long-term use of dual antiplatelet treatment (DAPT) is mandatory. The tested nano-coating has been shown to reduce material thrombogenicity and promote endothelial cell proliferation in vitro. We compared the biocompatibility of coated (Derivo Heal) and non-coated (Derivo bare) FDs with DAPT in an animal model. Methods Derivo® bare (n = 10) and Derivo® Heal (n = 10) FD were implanted in the common carotid arteries (CCAs) of New Zealand white rabbits. One additional FD, alternately a Derivo bare (n = 5) or Derivo Heal (n = 5), was implanted in the abdominal aorta (AA) for assessment of the patency of branch arteries. Histopathological examinations were performed after 28 days. Angiography was performed before and after FD implantation and at follow-up. Results Statistical analysis of the included specimens showed complete endothelialization of all FDs with no significant differences in neointima thickness between Derivo® bare and Derivo® Heal (CCA: p = 0.91; AA: p = 0.59). A significantly reduced number of macrophages in the vessel wall of the Derivo Heal was observed for the CCA (p = 0.02), and significantly reduced fibrin and platelet deposition on the surface of the Derivo Heal was observed for the AA. All branch arteries of the stented aorta remained patent. Conclusion In this animal model, the novel fibrin-based coated FD showed a similar blood and tissue compatibility as the non-coated FD

Client-server optimization for multimedia document exchange

The success of the World Wide Web is boosting the development of multimedia database systems and their integration into the internet. For the documents stored and exchanged in the Web there is a variety of multimedia data formats differing in aspects such as resolution, sampling rate, and compression. Furthermore there is a large heterogeneity of Web browsers, the data formats they support, and their network access. Thus storage servers have to store and proxy servers have to transfer many different formats. However, the data formats are not independent from each other but interrelated by conversion tools. There is a large number of alternatives for storage and proxy servers to store some formats or to transfer them via the network and to compute the remaining ones by applying conversion tools. To determine an optimal choice is a nontrivial optimization problem and is subject to changes of the parameters such as query profile, available disk storage, and network bandwidth. We examine the outlined optimization problem in the context of object-oriented databases and illustrate our approach by a practical application

Subtyping by constraints in object-oriented databases

For many object-oriented database applications taxonomies with a setinclusion semantics among the type extents are essential. In practical cases, however, common object-oriented modeling techniques often do not result in taxonomies as they ignore application specific constraints. We will elaborate that especially in domains like CAD or similar engineering environments integrity constraints on type attributes have a deep impact on the resulting hierarchy. We argue that subtyping by constraints may be superior to other object-oriented alternatives like subtyping for generalization or nearly-flat hierarchies. Subtyping by constraints achieves a logical set-inclusion hierarchy, and in addition enables a larger amount of semantically correct substitutability. This can even be improved by a novel framework of automatic method adaptation for enhanced substitutability