Vibrations of Layered Beams under Conditions of Damaging and Slipping Interfaces

A nonlinear laminate layerwise beam theory is developed to simulate the effect of inelastic interlayer slip on the stiffness degradation of layered beam structures. Layerwise continuous and linear in-plane displacement fields are implemented. It is shown that by definition of an effective cross-sectional rotation the complex problem reduces to the simpler case of a homogenized shear-deformable beam with effective stiffness and a corresponding set of boundary conditions. Inelastic defects of the interlayer material are equivalent to eigenstrains in an identical but unlimited elastic background structure of the homogenized beam with proper effective virgin stiffness. Cross-sectional resultants of these eigenstrains are defined. Since the incremental response of the background to the given load and to the properly imposed eigenstrain increments is considered to be linear within a given time step, effective solution methods of the linear theory of flexural vibrations become applicable. This revised version was published online in July 2006 with corrections to the Cover Date.     

eIDs und Identitätsmanagement

Zusammenfassung  Mit der Einführung des elektronischen Personalausweises steht in Deutschland eine eID-L?sung mit potentiell sehr weiter Verbreitung vor der Tür. Der Beitrag diskutiert, wie solche L?sungen im Identit?tsmanagement eingesetzt und wie sie in Zukunft verbessert werden k?nnen. Dr. Christoph Sorge Research Scientist, NEC Laboratories Europe, Heidelberg. T?tigkeitsschwerpunkt: Forschung im Bereich der Netzsicherheit, u.a. Identit?tsmanagement Dr. Dirk Westhoff Chief Researcher, NEC Laboratories Europe, Heidelberg. T?tigkeitsschwerpunkt: Forschung in den Bereichen mobile drahtlose Sicherheit, Identit?tsmanagement     

eHealth: Welchen Nutzen erwartet der Bürger?

Es gibt einen breiten Konsens, dass auch in der Gesundheitsversorgung Papier gebundene Kommunikation durch elektronische Medien ersetzt werden muss. Erwartungen und Nutzen für die verfassten Organisationen sind bereits gefestigt. Wie wird der Bürger in diese Entwicklung eingebunden?     

Distribution of costs induced by the integration of RES-E power

This article focuses on the distribution of costs induced by the integration of electricity generation from renewable energy sources (RES-E). The treatment to distribute these costs on different market actors is crucial for its development. For this purpose, individual actors of electricity markets and several cost categories are identified. According to the defined cost structure, possible treatments to distribute the individual cost categories on different relevant actors are described. Finally, an evaluation of the cost distribution treatments based on an economic analysis is given. Economic efficiency recommends that clearly attributable (shallow) grid connection as well as (deep) grid costs are charged to the corresponding RES-E producer and that the RES-E producers are also charged the regulating power costs. However, deep grid integration costs should be updated to reflect evolving scarcities. Also regulating power costs should reflect actual scarcity and thus be symmetric and based on real-time prices, taking into account the overall system imbalance. Moreover, the time span between the closure of the spot market and actual delivery should be chosen as short as possible to enable accurate RES-E production forecasts.     

3-D face recognition for unattended access control

Biometric data have been integrated in all new European passports, since the Member States of the European Union started to implement the EU Council Regulation No 2252/2004 on standards for security features and biometrics in passports. The additional integration of three-dimensional models promises significant performance enhancements for border controls. By combining the geometry-and texture-channel information of the face, 3-D face recognition systems provide an improved robustness while processing variations in poses and problematic lighting conditions when taking the photo.     

Sequential learning to accelerate discovery of alkali-activated binders

Journal of Materials Science - Alkali-activated binders (AAB) can provide a clean alternative to conventional cement in terms of CO2 emissions. However, as yet there are no sufficiently accurate...     

Reconfiguration of Amorphous Complex Oxides: A Route to a Broad Range of Assembly Phenomena,Hybrid Materials,and Novel Functionalities

Reconfiguration of amorphous complex oxides provides a readily controllable source of stress that can be leveraged in nanoscale assembly to access a broad range of 3D geometries and hybrid materials. An amorphous SrTiO₃ layer on a Si:B/Si_1?xGe_x:B heterostructure is reconfigured at the atomic scale upon heating, exhibiting a change in volume of ≈2% and accompanying biaxial stress. The Si:B/Si_1?xGe_x:B bilayer is fabricated by molecular beam epitaxy, followed by sputter deposition of SrTiO₃ at room temperature. The processes yield a hybrid oxide/semiconductor nanomembrane. Upon release from the substrate, the nanomembrane rolls up and has a curvature determined by the stress in the epitaxially grown Si:B/Si_1?xGe_x:B heterostructure. Heating to 600 °C leads to a decrease of the radius of curvature consistent with the development of a large compressive biaxial stress during the reconfiguration of SrTiO₃. The control of stresses via post-deposition processing provides a new route to the assembly of complex-oxide-based heterostructures in 3D geometry. The reconfiguration of metastable mechanical stressors enables i) synthesis of various types of strained superlattice structures that cannot be fabricated by direct growth and ii) technologies based on strain engineering of complex oxides via highly scalable lithographic processes and on large-area semiconductor substrates.