Imaging of Polarons in Ferromagnetic Bilayered Manganites by Scanning Tunnelling Microscopy

We report scanning tunnelling microscopy images of polaronic charge ordered patch on the layered ferromagnet La_2−2x Sr_1+2x Mn₂O₇, x=0.32. The spectroscopic investigation shows that the material is gapped above and below the critical temperature, where the gap changes from 500 to 800 mV, giving evidence for polaronic transport behaviour. This work has been supported by European Project No. 517039 CoMePhS (Controlling Mesoscopic Phase Separation).     

OFDM-Based Overlay Systems: A Promising Approach for Enhancing Spectral Efficiency [Topics in Radio Communications]

Recently, several approaches for increasing spectral efficiency have been proposed to overcome the scarcity of spectral resources and to ensure that the ever-growing demand for high-data rate mobile communications can be met in the future. In this article, we focus on OFDM-based overlay systems that share a frequency band with already existing systems without degrading their performance. This is achieved by temporarily using those parts of the common frequency band that are currently not used by the licensed system. In particular, we focus on design issues for the physical layer as well as the medium access control layer and propose appropriate solutions for enabling coexistence. As a result, our investigations show that OFDM-based overlay systems are a promising approach for enhancing spectral efficiency.     

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     

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.