Der PC in zehn Jahren und seine Auswirkungen auf die Gesellschaft

In this article it is argued that in ten years’ time personal computers as we know them now won’t exist anymore — all their functions will by then be integrated in mobiles which will be our steady companions. As such, mobiles will change our lives to an enormous extent. Technology as well as consequences will be discussed in this paper.     

Possibilities and extension of XRD material response analysis in failure research for the advanced evaluation of the damage level of Hertzian loaded components

Due to clearly distinguishable damage symptoms, it is differentiated between the surface and sub‐surface failure mode of rolling bearings. Material states red out by X‐ray diffraction (XRD) residual stress measurements point to a variety of loading conditions especially at raceway surfaces that are associated with several competing failure mechanisms. The corresponding lifetime reduction can range from the lower fatigue strength region to material ratcheting in extreme cases. Relevant position of the microstructural changes and nature of the failure mechanisms are characterized. The time alteration of the XRD material parameters measured at or near the surface and at the depth of the maximum equivalent stress correlates, in a different manner, with the statistical parameter of the 10 % bearing life. Both failure modes are illustrated by concrete examples. Contaminated lubricant and boundary lubrication, which represent practically important surface‐induced failures, are discussed in more detail. Gray staining, i.e. shallow pitting, often occurs without distinct indication of global material aging by means of XRD characteristics. Here, scanning electron microscopy observations and electron microprobe analyses point to corrosion fatigue as acting surface failure mechanism. The interaction between material and lubricant under complex loading regimes particularly of mixed friction and corrosion opens further failure research areas in the field of tribology.     

Referenzprozesse für elektronische Ausschreibungen aus Sicht des industriellen Einkaufs

Many companies and purchasing departments only possess a limited knowledge about the modelling of inter-company business processes for electronic procurement. In the past the discussion about electronic procurement was mostly focused on technical aspects. This article introduces a reference process model for procurement auctions. The process model is made up of a basic process, which describes a minimal process for procurement auctions, and a number of process alternatives, which allow for the adoption of the basic process to changing parameters and individual company requirements.     

Radiale Wärmeleitung in durchströmten Schüttungsrohren

Heat Transport to the Wall of Packed Tubes. Radial conduction of heat in packed tubes has a crucial influence on yield and selectivity of many heterogeneously catalyzed reactions. In spite of many years of intensive research in the field, there are still tremendous discrepancies between correlations of different origin. Even the standard model using two constant heat transport parameters, which was introduced in the fifties and has since become most widely accepted, has been controversially discussed and called into question. The unsatisfactory state of the art has been an incentive for several groups of researchers to take up this old topic once again. Three parallel experimental investigations on heat transport with air flowing in packed tubes of similar dimensions, electrically heated, steam-heated, or water-cooled, were completed in 1991. Comparative evaluation of the results of these three investigations, together with other data from the relevant literature, now provides the first clear answers to some of the questions so controversially discussed in the past.     

Maternal complications from tocolytic treatment with beta-mimetics. Three cases of pulmonary edema

We report three cases of pulmonary edema associated with prolonged intravenous tocolytic therapy with beta 2-adrenergic agonists among patients with multiple pregnancies. Although beta 2-adrenergic agonists may have direct myocardial side-effects, the underlying pathophysiologic mechanisms are mainly noncardiogenic. The most important one appears to be the fluid overload, related to amounts of fluids given intravenously and to direct result of beta-sympathomimetic therapy on renal excretion of sodium and water. Neonatal benefit of prolonged tocolytic therapy remains hypothetical. If this strategy is used, the prevention of cardiovascular adverse effects requires an intensive maternal supervision, especially in case of multiple pregnancy, the use of beta 2-adrenergic agonists in concentrated solution in order to reduce the amounts of fluids given intravenously, and the association with progesterone therapy which can reduce the infusion rate and the duration of tocolytic therapy.     

An efficient implementation of certain iterative refinement preconditioners

Preconditioned iterative methods of conjugate gradient type for solving elliptic and parabolic problems discretized on grids wth local refinement are considered. The sparsity pattern of the residuals computed throughout the iterative process is investigated. It turns out that they are nonzero only near the interface nodes between the coarse-and fine-grids. This observation is used to formulate the preconditioned CG, and when the matrix is not symmetric as in the parabolic case—the generalized CG and GMRES methods, thus substantially saving storage and computation.     

A local solution method for shock boundary-layer interaction on a swept wing

Summary The paper describes a local solution method for the calculation of the interaction between a weak shock front and a turbulent boundary layer on a swept wing. A multiple-deck approach allows the simplification of the governing equations according to the physical character of each deck. The mathematical model is based upon small-perturbation theory. The final boundary-layer solution is given by an iterative coupling of the solutions for each domain. The results are compared with experiments and with other theoretical solutions.     

Heading towards an advanced signalling system for multimedia,multiparty services in broadband ISDN

Introduction of the broadband integrated services digital network (B-ISDN) will enable network users to make use of advanced multimedia, multiparty services. With this aim in view, RACE II project R2044, MAGIC, is investigating long-term signalling requirements, architecture and protocols for B-ISDN. New service concepts are being developed in MAGIC which will provide more flexibility when compared to narrowband ISDN (N-ISDN). The service requirements and other signalling requirements, such as the separation between call and associated connections at the network-node interface, are used to determine the distribution of functions over the network. The signalling protocols which are used to exchange the signalling information are subsequently developed. These signalling protocols are simulated to prove the performance and the feasibility of call handling concepts