Mode I fracturing properties of epoxy bonding paste

The wedge-splitting method by Tschegg was applied for the investigation of mode I fracture behavior of epoxy-based adhesives. Specific fracture energy and notch tensile strength of “traditional” thickened laminating resin were measured between −40 and +45 °C and compared to those of four new trial compounds. The adhesives in bulk were investigated as well as the interfaces between these adhesives and glass fiber-reinforced plastic. The wedge-splitting method has turned out suitable for epoxy resin. The quality of thickened laminating resin was not reached by the new trial compounds. Adherend pre-treatment with laminating resin and peel ply improved interfacial properties.     

Complementary Ways to Diastereomers of Bridged Aminopiperidine Derivatives — A Stereochemical Challenge

Routes to diastereomers of constrained 4‐amino‐piperidines — a common pharmaceutically used diaminic building block — are realized mainly on the basis of CN‐double bond species or their radicalic or anionic analogues. Kinetically controlled reactions on the one hand and thermodynamic control of reactions, reversible introduction of a repulsive group, direction of a reactant by intramolecular complexation, or involvement of radicalic or anionic intermediates with strong isomerization tendency on the other hand are the tools for a complementary accessibility of both diastereomers.     

Relativistic many-body Møller-Plesset perturbation theory calculations of the energy levels and transition rates in Na-like to P-like Xe ions

Relativistic multireference many-body perturbation theory calculations have been performed for Xe⁴³⁺ to Xe³⁹⁺ ions, resulting in energy levels, electric dipole transition rates, and level lifetimes. The second-order many-body perturbation theory calculation of energy levels included mass shifts, the frequency-dependent Breit correction, and Lamb shifts. The calculated transition energies and E1 transition rates are used to present synthetic spectra in the extreme ultraviolet range for some of the Xe ions.     

Teil 2: Trittschalldämmung — Flankentrittschallpegel und Trittschallminderung

Sound protection of cavity floors. Part 2: Impact sound insulation — namely impact sound flanking level and impact sound reduction In part 1 [1] of this three‐part report on cavity floor sound protection, the history of the development of cavity floors introduced on the market since the early 1980s, the main design principles of such floors, and the concepts of flanking level reduction and weighted standard flanking level difference were illustrated. This second part examines two aspects of impact sound insulation, namely impact sound flanking level — previously sometimes referred to as horizontal impact sound insulation — and impact sound reduction. The following discussion of these two impact sound insulation parameters is based on approximately 150 measurements in an acoustics laboratory. The bulk of the measurements was carried out according to DIN 52 210 [3], more recent measurements according to DIN EN ISO 140‐12 [4].     

Teil 3: Anwendung von Laborergebnissen in der Baupraxis,Ausführungsfehler

Sound protection of cavity floors. Part 3: Application of laboratory results in practice; pitfalls during construction This third part of the three‐part „Sound protection of cavity floors”︁ series relates the laboratory examination and analysis of the acoustic parameters of cavity floors to the application in practice. Part 1 [1] described the historic development of cavity floors since the 1980s and the main airborne sound protection parameters, i.e. the standard flanking level difference (airborne sound protection for horizontal transfer, flanking level reduction) and the sound insulation of solid ceilings with cavity floors for vertical sound transfer. Part 2 of the series [2] described the impact sound insulation parameters, i.e. the weighted impact sound reduction (impact sound improvement) and the weighted flanking impact sound level (weighted standard impact sound level for horizontal transfer). This third part suggests cavity floor design options for meeting the required sound protection levels that may exist either in the form of minimum requirements stipulated by building authorities or through civil law agreements between users and investors.     

Schallschutz mit schalldämmenden Lüftungsgittern

Sound protection using sound‐absorbing ventilation grilles. Sound‐absorbing ventilation grilles are used for supply and exhaust air openings in buildings, in naturally ventilated multistorey car parks, and for screening noise‐emitting equipment requiring a flow of air. The sound insulation of different ventilation grilles was measured in the laboratory. A nomogram taking account of the gap length and width was developed for estimating the weighted sound reduction index of typical sound‐absorbing ventilation grilles. Suggested spectrum adjustment values for the weighted sound reduction index are provided.     

Multiservices MAC‐protocol for wireless ATM

ATM is the future networking technology in the area of broadband networks. Using fiber optical cabling offers high bandwidth and low error rates. It is supposed to support different kinds of services, e.g., file transfer, videoconferencing, and speech transmissions. To support seamless end-to-end quality of service in a mobile environment a suitable extension to the fixed network part is necessary. In a wireless ATM environment the medium access protocol takes a prominent position. It is responsible for an efficient and fair media access on the shared radio resource. Due to the limited available bandwidth and the much higher error rates on the radio link special provisions must be provided. The compliance of traffic contracts for connections with different quality of services is the aim of our proposed protocol. This is the base of true end-to-end services with quality of service assurance in wireless ATM. This revised version was published online in June 2006 with corrections to the Cover Date.     

Schallschutz von Bauteilen aus mineralischen Baustoffen in Abhängigkeit von der Abbindezeit

Sound protection of structural components made from mineral materials as a function of the setting time. For structural components made from mineral materials, e.g. slabs and walls made from masonry or concrete, screed or cavity floors, the acoustic properties relating to impact and airborne sound protection are expected to change over time. This is due to the fact that the strength increases during the setting process while the mass decreases during the drying process. This article describes the sound insulation characteristics of typical structural components over time during the setting/drying process and defines the intervals after which the state reached after 28 days can be determined with acceptable accuracy.     

Interactive rigid body manipulation with obstacle contacts

The interactive manipulation of rigid objects in virtual reality environments requires an object behaviour which is at least physically plausible to be useful for applications such as interactive assembly simulation and virtual training. Physically plausible behaviour implies that collisions between simulated solid objects are taken into account and that the motion of objects with obstacle contacts can be controlled without force feedback mechanisms in an intuitively correct manner. We present a real time framework which enables the simulation of interactively controlled solid objects with a dynamically changing set of contact constraints. In this paper all contact configurations are replaced by a canonical set of point contacts which is updated dynamically. The basic step to determine the contact forces and object motion consists in the solution of a non-linear complementarity problem (NCP), which results from the unilateral contact conditions together with an adequate discretization of the corresponding differential equations of motion. © 1998 John Wiley & Sons, Ltd.     

An Approach to Calculating Wear on Annular Non‐Return Valves

The serviceability of non‐return valves has a major influence on the productivity of the injection molding process. During a meeting of experts held at our Institute, it was seen that closing behavior and wear are the key problems encountered in practice. The conducted investigations to tackle these questions have shown that both an improved closing behavior and a lower level of wear can be achieved by reducing the inside radius of the locking ring.

Pressure profile over the length of a non‐return valve (n = 0.4; = 25 000 mm³/s).