Model checking action system refinements

Action systems provide a formal approach to modelling parallel and reactive systems. They have a well established theory of refinement supported by simulation-based proof rules. This paper introduces an automatic approach for verifying action system refinements utilising standard CTL model checking. To do this, we encode each of the simulation conditions as a simulation machine, a Kripke structure on which the proof obligation can be discharged by checking that an associated CTL property holds. This procedure transforms each simulation condition into a model checking problem. Each simulation condition can then be model checked in isolation, or, if desired, together with the other simulation conditions by combining the simulation machines and the CTL properties.     

Human-factors engineering for smart transport: design support for car drivers and train traffic controllers

The theme Smart Transport can be described as adequate human-system symbiosis to realize effective, efficient and human-friendly transport of goods and information. This paper addresses how to attune automation to human (cognitive) capacities (e.g. to take care of information uncertainty, operator trust and mutual man-machine adaptations). An introduction to smart transport is presented, including examples of best practice for engineering human factors in the vehicle ergonomics and train traffic control domain. The examples are representative of an ongoing trend in automation and they show how the human role changes from controller to supervisor. Section 2 focuses on the car driver and systems that support, or sometimes even take over, critical parts of the driving task. Due to the diversity of driver ability, driving context and dependence between driver and context factors, there is a need for personalised, adaptive and integrated support. Systematic research is needed to establish sound systems. Section 3 focuses on the train dispatcher support systems that predict train movements, detect potential conflicts and show the dispatcher the possibilities available to solve the detected problems. Via thorough analysis of both the process to be controlled and the dispatcher's tasks and cognitive needs, support functions were developed as part of an already very complex supervision and control system. The two examples, although from a different field, both show the need for further development in cognitive modelling as well as for the value of sound ergonomics task analysis in design practice.     

Lanthanzirkonat: ein innovatives Wärmedämmschichtmaterial. Lanthanum zirconate: an innovative Thermal Barrier Material

This paper presents the work of the research project AiF‐13114 N/1. Within the scope of this project coating systems from Lanthanum Zirconate and Y ttria s tabilised Z irconia (YSZ) were developed by use of E lectron B eam P hysical V apour D eposition (EB‐PVD). In addition, the potentials of Lanthanum Zirconate and YSZ as thermal barrier coatings within gas turbines were examined. Basis of the coating development was the use of powdery Lanthanum and YSZ, that were vaporised in a PVD‐machine from a double‐grooved cupreous crucible. Process parameters are evaluated to gain long lasting, columnar Lanthanum Zirconate EB‐PVD coatings with high stability, low heat conductivity a higher sintering inertness, that offer the opportunity to increase the temperature within the first stage of a gas turbine system [1, 2, 3, 4, 5, 6]. Therefor YSZ ‐ commonly used as conventional thermal barrier coating ‐ was used as a reference system during the tests. As base material Inconel Alloy 600 (a nickel‐based superalloy) was applied. The microstructure and the topography of the developed coating systems were characterized with the help of scanning electron microscopy. Nanoindentation proved to be a measurement method in order to define the stiffness distribution along the columns. The thermal cycle durability was determined via thermal cycle test.     

KSpaceNavigator as a tool for computer-assisted sample tilting in high-resolution imaging, tomography and defect analysis

This article describes a novel software tool, the KSpaceNavigator, which combines sample stage and crystallographic coordinates in a control sphere. It also provides simulated kinematic diffraction spot patterns, Kikuchi line patterns and a unit cell view in real time, thus allowing intuitive and transparent navigation in reciprocal space. By the overlay of experimental data with the simulations and some interactive alignment algorithms, zone axis orientations of the sample can be accessed quickly and with great ease. The software can be configured to work with any double-tilt or tilt–rotation stage and overcomes nonlinearities in existing goniometers by lookup tables. A subroutine for matching the polyhedral shape of a nanoparticle assists with 3D analysis and modeling. The new possibilities are demonstrated with the case of a faceted BaTiO₃ nanoparticle, which is tilted into three low-index zone axes using the piezo-controlled TEAM stage, and with a multiply twinned tetrahedral Ge precipitate in Al, which is tilted into four equivalent zone axes using a conventional double-tilt stage. Applications to other experimental scenarios are also outlined.     

From utility disconnection to universal access

By some estimates, 31% of Americans face some sort of ‘energy insecurity,’ but the full extent of the issue and the magnitude of its effect are often difficult to quantify. This case study examines disconnection policies primarily in Minnesota and attempts to extrapolate lessons learned for other states and the nation as a whole. The case study concludes with a discussion about the relevance of U.S. universal access to the utility shut-off challenge.     

Stiff gelatin hydrogels can be photo-chemically synthesized from low viscous gelatin solutions using molecularly functionalized gelatin with a high degree of methacrylation

Gelatin is a very promising matrix material for in vitro cell culture and tissue engineering, e.g. due to its native RGD content. For the generation of medical soft tissue implants chemical modification of gelatin improves the mechanical properties of gelatin hydrogels and the viscous behavior of gelatin solutions for liquid handling. We present a systematic study on the influence of high degrees of methacrylation on the properties of gelatin solutions and photo-chemically crosslinked hydrogels. Changes from shear thinning to shear thickening behavior of gelatin solutions were observed depending on mass fraction and degree of methacrylation. Degrees of swelling of crosslinked hydrogels ranged from 194 to 770?% and storage moduli G′ from 368 to 5?kPa, comparable to various natural tissues including several types of cartilage. Crosslinked gels proofed to be cytocompatible according to extract testings based on DIN ISO 10933-5 and in contact with porcine chondrocytes.     

Design and implementation of multiaxial force sensing gripper fingers

This paper focuses on the integration of elementary force sensors into the fingers of parallel grippers. The theory of the approach of integrating three sensor elements into a gripper finger is described and the results of the practical evaluations are given. Strain gauges are used as elementary sensor elements. Two different design approaches are evaluated. The first one uses H-shaped cut-outs to weaken the structure at designated areas. The measurement accuracy of this system is compared with a second approach without cut-outs, which is easier to manufacture. Finite element analysis is used in both approaches to simulate the behaviour and to determine the best locations for strain gauge application. The performances of both design concepts are experimentally evaluated. It can be seen that the results of the finite-element analysis are correct and that a satisfactory decoupling of the basic sensors can be achieved using a physical or mathematical approach. Both prototypes are able to measure the gripping force with sufficient accuracy.     

Detection of Salmonella in food,feed and veterinary samples by EU laboratories

The European Union Reference Laboratory (EURL) for Salmonella organises interlaboratory comparison studies on bacteriological detection of Salmonella in different matrices (veterinary, food and animal feed) amongst National Reference Laboratories for Salmonella of the 27 European Member States (EU-MS). The EURL also gives non-EU Member States (EU candidate countries, member countries of the European Free Trade Association (EFTA) and third countries from outside Europe) the opportunity to participate in these studies. The objective of the studies is to test the ability of the participating laboratories to detect Salmonella at different contamination levels in the various matrices. In addition a comparison is made between the prescribed method of the food and animal feed studies (ISO 6579: RVS and MKTTn) and the prescribed method of the veterinary studies (annex D of ISO 6579: MSRV).This article describes the performance of the individual laboratories in the interlaboratory comparison studies as organised by the EURL for Salmonella in the period 2004-2010.The performance of the majority of the NRLs improved during the course of the studies. Overall the NRL laboratories performed well and were able to detect Salmonella in the different tested matrices. After improvement of the samples, it was possible to define criteria for good performance in the studies organised since 2006. In the eight interlaboratory comparison studies organised in the period 2006–2010, 15 laboratories found in total 19 deviations of which eight concerned a false positive blank result. The other deviations concerned sensitivity problems (false negative results). After checking and improving several technical aspects, the underperforming participating laboratories were able to improve their performance in a follow-up study.     

Mechanism and dynamics of shrinking island grains in mazed bicrystal thin films of Au

This work investigates the mechanism and dynamics of grain boundary migration driven by capillary forces via in situ electron microscopy, complemented by molecular-dynamics simulations. Using thin films of Au with the mazed bicrystal geometry, the shrinkage of island grains with 90°〈1 1 0〉 tilt grain boundaries was observed by diffraction contrast and high-resolution imaging. The grains remained cylindrical throughout the shrinkage, and there was no measurable grain rotation even at very small sizes. The rate of shrinkage was found to be erratic and inconsistent with parabolic kinetics, accelerating before complete disappearance. Residual defects were found immediately after complete shrinkage, although the type and magnitude of the defects varied from grain to grain. Measurement of the grain boundary shape anisotropy showed a preference for facets on low-index planes of the crystals, including the mirror-symmetry planes of the bicrystal. These facets were also found directly on individual images extracted from high-resolution video recordings of shrinking grains at ～300 °C. The dynamics of boundary motion were found to be limited by nucleation and propagation of steps on these facets. The cylindrical geometry and size of the experimentally observed island grains allow direct comparison with molecular-dynamics simulations on the same length scale, which reproduced many of the experimentally observed features, including non-parabolic shrinkage, absence of systematic grain rotation, step-controlled migration and dislocation debris after complete grain shrinkage. Differences between model and experiment are discussed in terms of the possible role of impurities, surfaces and interfacial steps.