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In the paper the method of discrete modeling (movable cellular automata method) and combined discrete-continuous description of the simulated medium are used to analyze processes occurring in the local contact of the automotive brake system. The characteristic size of the considered region is 1.5 μm. The following contact situation is simulated: steel fiber coated by an iron oxide film as the brake pad and pearlitic steel also coated by an iron oxide layer as the disc. On the assumption of oxide layer wearing we simulate the iron oxide - iron oxide, iron oxide - metal and metal - metal contacts. The calculation results for the friction coefficient for various contact situations give quite adequate values. For example, for the oxide - oxide system the calculated coefficient is approximately equal to 0.4, while for the metal - metal contact the obtained value varies from 0.7 to 0.9. Analysis of a set of the obtained results allows concluding that oxide is formed more rapidly than the sliding layer, which in turn makes the friction coefficient value stabilized.

Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG geförderten) Allianz- bzw. Nationallizenz frei zugänglich. This publication is with permission of the rights owner freely accessible due to an Alliance licence and a national licence (funded by the DFG, German Research Foundation) respectively. Light-pipes described in this paper guide light along an axis allowing it to escape from its surface for illumination purposes. Light is coupled into them by a beamer luminaire. The performance of a hollow light guide very much depends on the quality of the materials used to guide the light. The luminous characteristics of these materials influence a light-pipe’s overall performance. The first section of this paper describes measurement techniques for light incidence resolved measurements on materials. Common co-ordinate systems for describing the geometry and a data format to store the data are shown. The second section of this paper deals with light-pipe goniophotometry. A goniophotometer for light-pipes has been constructed at the Technical University of Berlin. To evaluate the results measurements are compared to these from a real installation.

Die Verwendung von Kugelkopfen und Pfannen aus Aluminiumoxidkeramik reduziert die Abriebrate beim Huftgelenkersatz. Der klinische Einsatz von Zirkonoxidkeramiken (Y-TZP) wird kontrovers diskutiert. Die Vorgange an den Artikulationsflachen Kopf/Pfanne sind nicht vollstandig verstanden, besonders die durch Reibwarme verursachte Temperaturerhohung. Bei den phasenstabilen Aluminiumoxidkeramiken werden keine ungunstigen Effekte beobachtet. Bei Y-TZP dagegen kann durch reibbedingte Temperaturerhohungen die Gerinnungstemperatur der Gelenkflussigkeit uberschritten, bzw. die Phasenumwandlung des Y-TZP ausgelost werden. Mit Hilfe des Modells von Kuhlmann – Wilsdorf sind unter in vivo Randbedingungen die Blitztemperaturen in den Mikrokontakten der verschiedenen keramischen Artikulationspartner bestimmt worden. Die zugehorigen realen Kontaktbedingungen wurden mit den analytischen Modellvorstellungen nach Grennwood – Williamson berechnet. Die Oberflachentemperaturen sind fur die Gleitpaarung Y-TZP/Y-TZP hoher als fur Al2O3/Al2O3. Calculation of Flash Temperatures of Micro-Contacts in Artificial Hip Joints by Using the Contact Model of Greenwood – Williamson In hip replacement the wear rate is reduced when using femoral heads and acetabular cups made of alumina ceramics. The use of zirconia ceramics (Y-TZP) is discussed controversy. The process on the articulating surfaces head / cup are not totally understood, especially the temperature rise due to frictional heating. Alumina is a stable material, no problems are expected. When using Y-TZP, friction temperature can be higher then the coagulate temperature of synovia or the phase transition is induced. The model proposed by Kuhlmann – Wilsdorf was used to calculate the flash temperature under in vivo conditions of micro-contacts at the different articulating surfaces. The real contact conditions were calculated with the analytical contact model of Greenwood – Williamson. The surface temperature of the wear couple Y-TZP/Y-TZP was higher than the one for alumina/alumina.

In hip replacement the wear rate is reduced when using femoral heads and acetabular cups made of alumina ceramics. It is proposed to use Y-TZP zirconia ceramics. The process on the articulating surfaces head/cup are not totally understood, especially the temperature rise due to frictional heating. Alumina is a stable material, no problems are expected. When using Y-TZP its phase transition may he triggered due to frictional heating and the leaching out of yttria. The model proposed by Blok, Jaeger and Kuhlmann-Wilsdorf was used to calculate the flash temperature under in vivo conditions. The surface temperature of the wear couple Y-TZP/Y-TZP was higher than the one for alumina/alumina.

In order to deliver a foundation for orientation and decisions in the growing field of Mobile Augmented Reality (MAR), this chapter intends to deliver a realistic picture about MAR, where it comes from, where it currently stands, and where it is going. It distinguishes between the variants of MAR, explains their similarities, differences, and different development stages and outlooks. While describing potential application fields and their current limitations, the opportunities and challenges of MAR become obvious, as well as how much work is still to do. The chapter intends to categorize the challenges for MAR, covering also related issues in the mobile hardware, software, and operator industry, and their efforts in standardization and open interfacing. Besides the technology-driven discussion, a strong emphasis will be taken also to the essential aspect of user experience. With ubiquitous MAR, the technology will become more and more secondary, and the user and her individual context moves into the center of attention.

Tyrosine kinases are involved in cell signalling of growth factors such as insulin and insulin-like growth factor (IGF-I) and others. Insulin and IGF-I receptors which possibly feedback on insulin release are established in insulin-secreting cells. The role of tyrosine kinase in insulin secretion is controversial. Both the tyrosine kinase inhibitors tyrphostin 25 (TYR) and genistein (GEN), but not its structurally similar albeit biologically inactive analogue daidzein, increase insulin release at 16.7 mM glucose in INS-1 cells, an insulin secreting cell line. Tyrosine kinase activity is inhibited by GEN, but not diadzein. The inhibitory effects of either insulin or IGF-I on insulin release are abolished by 10(-4) M GEN but not by daidzein indicating an involvement of tyrosine kinase in the inhibitory effect of both insulin and IGF-I on insulin release. Since GEN was argued not to be specific for tyrosine kinase, several second messengers were investigated. cAMP is not influenced. The insulinotropic effect of acutely administered TPA is not influenced by GEN while in protein kinase C (PKC)-downregulated cells the insulinotropic effect of GEN is preserved: both indicate no involvement of PKC in GEN effect. Since pertussis toxin (PT) pretreatment has no effect on the inhibitory effects of IGF-I on insulin release, a PT-sensitive G-protein is not likely to be involved. The data indicate that tyrosine kinase is involved in the inhibitory effects of insulin and IGF on insulin release in INS-1 cells, possibly mediating the negative feedback effect.

Zur Aufstellung einer Kriechgleichung der Werkstoffsorte IN-939 werden aus einer umfangreichen Kriechdatensammlung mittlere Zeitdehngrenzkurven und Zeitbruchkurven gebildet und hieraus mittlere Kriechkurven abgeleitet. Auf deren Basis wird eine bereits fur einen Einzelwerkstoff erstellte Kriechgleichung an das durchschnittliche Kriechverhalten der Werkstoffsorte im gesamten anwendungsrelevanten Bereich angepast. Creep behaviour of some high temperature alloys Part 2: Creep equation of alloy IN-939 To establish a creep equation of alloy IN-939, an extensive creep data collection is evaluated to obtain mean creep curves. On this basis a creep equation of an individual test material is modified to describe the mean creep behaviour of alloy IN-939 in the whole range of application.

Fur hochwarmfeste Werkstoffe werden Gleichungen vorgestellt, die auf den Ergebnissen von Warmzug-, Zeitstand- und Gluhversuchen an einzelnen Versuchswerkstoffen beruhen und die elastoplastische Verformung, das Kriechen und die Kontraktion dieser Werkstoffe im gesamten, anwendungsrelevanten Temperatur-, Spannungs- und Zeitbereich beschreiben. Creep behaviour of some high temperature alloys Part 1: Creep equations of individual test materials For high temperature alloys equations are presented, which are based on the results of tensile, creep and annealing tests. The equations describe elastoplastic deformation, creep deformation and contraction of the materials in the whole temperature, stress and time range of application.

This chapter discusses the topic security in standard based virtual worlds with emphasis on X3D as the international ISO/IEC standard for Virtual Worlds. The general security challenges in persistent and economic virtual environments are addressed as well as the importance of standardization and security as the two key success factors for reliable, cost-effective and long-term attractive Virtual World (VW) platforms. Different actual standardization approaches are opposed to the established X3D format that follows a clear security standardization path. Based on the Internet standard XML the specific advantages of X3D are emphasized, like seamless integration into Web applications and deployment of generic XML tools. The generation of encrypted and signed X3D binary files is demonstrated according to the XML Security Recommendation of the W3C consortium. In a practical session the appliance of security approaches to concrete X3D implementation projects is described from the perspective of Bitmanagement (Bitmanagement, 2009), a market leader for interactive Web3D graphics software.

This chapter discusses the topic of standards for Virtual Worlds with emphasis on their usability as a stable and reliable basis for long-term investments into 3D-E-Commerce. The text explains why standards are important for the success of Virtual Worlds as well as the business in these shared online 3D environments, and what the relevant criteria are to decide for the right technology and/or provider. Although sometimes in the shadow of popular proprietary platforms there are already many different candidates for a Virtual World standard, currently in different states of development. By choosing a 3D platform, E-Commerce providers will decide about their business potential and at the same time strengthen one or another standard in the current technical competition phase. So it is important to get an overview about the current approaches, their advantages and disadvantages as well as the tendencies for the future developments. In this chapter the reader will be sensitized for the issues of standardization, compatibility and interoperability of Virtual Worlds for successful E-Commerce applications. An overview about the current approaches supports the orientation and decision for the different technologies. Some concrete XML-based code examples realized in the international ISO standard for interactive 3D-Graphics X3D demonstrates the practical deployment of highly compatible concepts. An outlook to the further integration of interactive 3D graphics into the Next Generation Web respectively the 3D Internet completes the overview.

The process of forming reaction layers of selected compounds is investigated regarding the chemical reactivity of different lubricants. The following lubricants were used as test oils: paraffin solutions with DBDS, ZDTP, acenaphthylene and limonene. Their influence on tribological behaviour is described for different conditions of friction. Relations between layer-forming behaviour and layer properties on the one hand, and tribological properties on the other hand, were shown by chemical layer profile analysis and other methods.

Gastrin-releasing peptide (GRP) receptors are present in pancreatic islets, though their regulation is unknown except for homologous desensitization. The modulation of binding of GRP to mouse pancreatic islets and INS-1 cells was studied. At 60 min (steady-state), total binding of [(125)I-Tyr(15)] GRP was 1.62 per cent of total radioactivity per 50 islets; non-specific binding (presence of 1 mM unlabelled GRP(1-27)) was 0.05 to 0.61 per cent of total radioactivity. A preincubation with 1000 nM cholecystokinin (CCK(8)) or with 1000 nM glucose-dependent insulinotropic peptide (GIP) augmented the number of GRP binding sites but not their affinity. [(125)I-Tyr(15)]GRP binding to INS-1 cells was saturable (90 min) and specific with respect to compounds that are not chemically related to GRP (e.g. calcitonin gene-regulated peptide-CGRP and atrial natriuretic peptide-ANP). Displacement studies showed one binding site with a K(d) of 0.39 nM and a B(max) of 13.2 fmoles mg(-1) protein. When the cells were pretreated for 24 h with 10 nM GIP or CCK(8), only GIP but not CCK(8) increased the B(max) of the GRP binding site. The affinity (K(d)) was not changed by either compound. This effect of GIP pretreatment was not affected by downregulating PKC by TPA (phorbol ester; long-term pretreatment). These data indicate that: (1) specific binding sites for GRP are present in mouse pancreatic islets and INS-1 cells; (2) the GRP binding is upregulated by GIP in both islets and INS-1 cells and additionally by CCK(8 ), albeit only in islets; and (3) PKC does not seem to be involved in the up-regulation process. Thus a positive interplay between both the incretins GIP and CCK(8) and the neurotransmitter GRP is obvious.

Im Mittelpunkt dieses Kapitels steht die Charakterisierung und Funktionsweise von Anleihen mit Fremdwahrungskomponente. Daruber hinaus werden auch die in der Literatur vertretenen Auffassungen bezuglich der Intentionen einerseits der Kaufer dieser Finanztitel und andererseits der Emittenten dargestellt. Diesen Ausfuhrungen kommt allerdings keinesfalls endgultige Bedeutung zu, da in den folgenden Kapiteln dieser Arbeit die Emissionsmotivation und die Bewertung aus Anlegersicht kritisch betrachtet und die ersten Einschatzungen in Frage gestellt werden.

Im Mittelpunkt dieses Kapitels steht die Finanzierungsentscheidung der Unternehmung. Im Zuge einer finanzierungstheoretischen Untersuchung soll die Motivation zu einer Finanzierung durch Anleihen mit Fremdwahrungskomponente analysiert werden. Dabei richtet sich das Interesse besonders auf die Auswirkungen der verschiedenen Finanzierungsinstrumente auf den Marktwert des Unternehmens, die Marktwerte von Eigenkapital und Fremdkapital, das Devisenkursrisiko und die Kapitalkosten der Unternehmung.