Algorithm for simulating fracture processes in concrete by lattice modeling

To simulate fracture behaviors in concrete more realistically, a theoretical analysis on the potential question in the quasi-static method is presented, then a novel algorithm is proposed which takes into account the inertia effect due to unstable crack propagation and meanwhile requests much lower computational efforts than purely dynamic method. The inertia effect due to load increasing becomes less important and can be ignored with the loading rate decreasing, but the inertia effect due to unstable crack propagation remains considerable no matter how low the loading rate is. Therefore, results may become questionable if a fracture process including unstable cracking is simulated by the quasi-static procedure excluding completely inertia effects. However, it requires much higher computational effort to simulate experiments with not very high loading rates by the dynamic method. In this investigation which can be taken as a natural continuation, the potential question of quasi-static method is analyzed based on the dynamic equations of motion. One solution to this question is the new algorithm mentioned above. Numerical examples are provided by the generalized beam (GB) lattice model to show both fracture processes under different loading rates and capability of the new algorithm.

Evaluating governance and participatory processes in Natura 2000: lessons learned and guidance for future prospects

In recent years, participatory approaches have been incorporated in decision-making processes as a way to strengthen the bonds between diverse areas of knowledge and social actors in natural resources management and environmental governance. Despite the favourable context, this paradigm shift is still in an early stage within the development of the Natura 2000 in the European Union, the largest network of protected areas in the world. To enhance the full scope of participatory approaches in this context, this article: (i) briefly reviews the role of participatory approaches in environmental governance, (ii) develops a common framework to evaluate such participatory processes in protected area management, (iii) applies this framework to a real case study, and (iv) based on the lessons learned, provides guidance to improve the future governance of Natura 2000 sites.

The omega failure in the crash-recovery model

190 p.

Ejection of energetic photoelectrons in laser-induced autoionisation: effects of high-order ionisation processes

Resonant interaction of an autoionising state with a strong laser field is considered and effects of second-order ionisation processes are investigated. The authors show that these processes play a very important role in laser-induced autoionisation (LIA). They drastically affect the lowest-order peaks in the photoelectron spectrum. In addition to these peaks, high-order peaks due to ejection of energetic photoelectrons appear. For the laser intensities of current interest, second-order peaks are much stronger than the original ones, an important result that, they believe, can be observed experimentally. Moreover, `peak switching', a general feature of above-threshold ionisation, is also manifest in the electron spectrum of LIA.

The Circulation of Monterey Bay and Related Processes

(PDF contains 114 pages)