Two CEGAR-based approaches for the safety verification of PLC-controlled plants

In this paper we address the safety analysis of chemical plants controlled by programmable logic controllers (PLCs). We consider a specification of the control program of the PLCs, extended with the specification of the dynamic plant behavior. The resulting hybrid models can be transformed to hybrid automata, for which advanced techniques for reachability analysis exist. However, the hybrid automata models are often too large to be analyzed. We propose two counterexample-guided abstraction refinement (CEGAR) approaches to keep the size of the hybrid models moderate.     

Long-term monitoring of polarization-mode dispersion of aerial optical cables with respect to line availability

Physical and technical limits become important when trying to increase data transfer rates to tens of gigabits and higher for already installed optical cables. Polarization-mode dispersion (PMD) is one of the crucial transmission constraints, especially for aerial cables exposed to environmental stresses. Optical fibers in the laboratory and three aerial optical fiber cable links across the Swiss alps were characterized with respect to PMD. Long-term measurement results are correlated to weather data along the cables, and predictions regarding line availability are made.     

Fabrication and electrical characterization of circuits based on individual tin oxide nanowires

Two-?and four-probe electrical measurements on individual tin oxide (SnO(2)) nanowires were performed to evaluate their conductivity and contact resistance. Electrical contacts between the nanowires and the microelectrodes were achieved with the help of an electron-?and ion-beam-assisted direct-write nanolithography process. High contact resistance values and the nonlinear current-bias (I-V) characteristics of some of these devices observed in two-probe measurements can be explained by the existence of back-to-back Schottky barriers arising from the platinum-nanowire contacts. The nanoscale devices described herein were characterized using impedance spectroscopy, enabling the development of an equivalent circuit. The proposed methodology of nanocontacting and measurements can be easily applied to other nanowires and nanometre-sized materials.     

Terahertz Multilayer Thickness Measurements: Comparison of Optoelectronic Time and Frequency Domain Systems

Journal of Infrared, Millimeter, and Terahertz Waves - We compare a state-of-the-art terahertz (THz) time domain spectroscopy (TDS) system and a novel optoelectronic frequency domain spectroscopy...     

In vitro hemocompatibility testing of new materials for mechanical heart valves

Biomaterials with improved wear properties, high resistance towards breaking, and better availability in comparison to the conventional material (PyroCarbon) may result in heart valve prostheses with prolonged lifetime and improved quality of life (no required lifetime anticoagulation). TiN-coatings as well as ceramic materials such as ZrO₂, and alternative carbon surfaces are considered as potential new materials. In order to determine hemocompatibility properties of these materials, a new test set-up without blood-air-contact has been built and successfully tested according to ISO 10993-4 : 1993 (EN 30993) within a first study for a series of materials.     

The offline software framework of the Pierre Auger Observatory

The Pierre Auger Observatory is designed to unveil the nature and the origins of the highest energy cosmic rays. The large and geographically dispersed collaboration of physicists and the wide-ranging collection of simulation and reconstruction tasks pose some special challenges for the offline analysis software. We have designed and implemented a general purpose framework which allows collaborators to contribute algorithms and sequencing instructions to build up the variety of applications they require. The framework includes machinery to manage these user codes, to organize the abundance of user-contributed configuration files, to facilitate multi-format file handling, and to provide access to event and time-dependent detector information which can reside in various data sources. A number of utilities are also provided, including a novel geometry package which allows manipulation of abstract geometrical objects independent of coordinate system choice. The framework is implemented in C++, and takes advantage of object oriented design and common open source tools, while keeping the user side simple enough for C++ novices to learn in a reasonable time. The distribution system incorporates unit and acceptance testing in order to support rapid development of both the core framework and contributed user code.