Feedback passivation of switched nonlinear systems using storage-like functions

This paper addresses the issues of passivity and feedback passivation of switched nonlinear systems via multiple storage functions. The concept of storage-like functions for switched systems is presented. A sufficient condition for passivity of switched nonlinear systems is given via multiple storage functions under some switching signal. Then, the result is extended to find conditions under which a switched system is feedback equivalent to a passive switched system. Furthermore, passivity of switched cascade systems is investigated.     

An Efficient State Recovery Attack on the X-FCSR Family of Stream Ciphers

We describe a state recovery attack on the X-FCSR family of stream ciphers. In this attack we analyse each block of output keystream and try to solve for the state. The solver will succeed when a number of state conditions are satisfied. For X-FCSR-256, our best attack has a computational complexity of only 2^4.7 table lookups per block of keystream, with an expected 2^44.3 such blocks before the attack is successful. The precomputational storage requirement is 2³³. For X-FCSR-128, the computational complexity of our best attack is 2^16.3 table lookups per block of keystream, where we expect 2^55.2 output blocks before the attack comes through. The precomputational storage requirement for X-FCSR-128 is 2⁶⁷.     

An equation-discovery approach to earthquake-ground-motion prediction

In active seismic regions an earthquake's peak ground acceleration (PGA) is required information when designing a building. In this study we employ the state-of-the-art, Lagramge, equation-discovery system to induce an equation that is suitable for modeling the PGA and investigate its applicability. In contrast to traditional modeling techniques the Lagramge system does not presume the structure of the equation and then identify the parameter values; instead, it finds the equation's structure as well. From the large amount of background knowledge on earthquake engineering we formalize a context-free grammar, which is then used as a guideline for the equation-building procedure. The PF-L data set used for the experiments is taken from the study of Peru? and Fajfar (2010), which is based on the data sets of Chiou et al. (2008) in the project Next Generation Attenuation of Ground Motion and the study of Akkar and Bommer (2010). The best model derived from the grammar is then quantitatively and qualitatively evaluated and compared. The presented results support the proposal to use an equation-discovery tool as an aid to the PGA modeling work and to potentially contribute new knowledge to the field of earthquake engineering.     

Beeinflussung der Eigenschaften warmgewalzter Tiefziehstähle durch gezielte Veränderung dex Stichplanes

Beeinflussung des Gefüges und somit der Eigenschaften eines beruhigten und eines unberuhigten Tiefziehstahles durch unterschiedliche aufeinanderfolgende Einzelformänderungen vor dem letzten Stich beim Warmwalzen. Stichplan und Abkühlungsgeschwindigkeit verändern die Korngrößengleichmäßigkeit über den Blechquerschnitt. Deutung der Versuchsergebnisse.     

Digging Deep into the Data Mine with DataMiningGrid

The growing computerization in modern knowledge and technology sectors is generating huge volumes of electronically stored data. Data mining technology is often employed to make sense of these data. However, as modern data mining applications increase in complexity, so do their demands for resources. Grid computing is one of several emerging networked computing paradigms promising to meet the requirements of heterogeneous, large-scale and distributed data mining applications. Despite this promise, there are still too many issues to be resolved before grid technology is commonly applied to large-scale data mining tasks. To address some of these issues, we developed the DataMiningGrid system, which principally differs from similar systems by its ability to integrate a diverse set of programs and application scenarios within a single framework. The system's key features include high performance and scalability, sophisticated support for relevant standards, different user types, and flexible extensibility. The software is available as open source.