A new concept for joining dissimilar composites

Bi-composite joint serves as interface between two dissimilar materials by interleaving plies of one composite with plies of another. This interleaving forms transition area between composites. Voids are filled in with epoxy resin to form strong, smooth transition between two materials

director profile of a nematic between two concentric cylinders with inhomogeneous boundary conditions

The tilt angle profile in a nematic cell limited by two concentric cylindrical surfaces with inhomogeneous distribution of easy axes is investigated in the one-constant approximation. The results are presented in terms of the Green function approach by considering the strong anchoring case and the presence of an external electric field for small distortions

Validation of Dam-Break Problem over Dry Bed using SPH

In this study, a comparison was made between experimental and numerical analysis results using the classical dam-break test case over dry bed. DualSPHysics software based on Smoothed Particle Hydrodynamics (SPH) method was used to make the numerical analysis. Experimental data were obtained from Kocaman [1]'s laboratory setup through image processing technique. It was observed that the numerical and experimental results are in good agreement

Formal support for QVT-Relations with Coloured Petri nets

The final publication is available at Springer via http://dx.doi.org/10.1007/978-3-642-04425-0_19Proceedings of 12th International Conference, MODELS 2009, Denver, CO, USA, October 4-9, 2009QVT is the OMG standard language for specifying model-to-model transformations in MDA. Even though it plays a crucial role in model driven development, there are scarce tools supporting the execution of its sublanguage QVT-Relations, and none for its analysis or verification. In order to alleviate this situation, this paper provides a formal semantics for QVT-Relations through its compilation into Coloured Petri nets, enabling the execution and validation of QVT specifications. The theory of Petri nets provides useful techniques to analyse transformations (e.g. reachability, model-checking, boundedness and invariants) and to determine their confluence and termination given a starting model. We also report on using CPNTools for the execution, debugging, and analysis of transformations, and on a tool chain to transform QVT-Relations specifications into the input format of CPNTools.Work supported by the Spanish Ministry of Science and Innovation, projects METEORIC (TIN2008-02081) and MODUWEB (TIN2006-09678

Parallel Recursive State Compression for Free

This paper focuses on reducing memory usage in enumerative model checking, while maintaining the multi-core scalability obtained in earlier work. We present a tree-based multi-core compression method, which works by leveraging sharing among sub-vectors of state vectors. An algorithmic analysis of both worst-case and optimal compression ratios shows the potential to compress even large states to a small constant on average (8 bytes). Our experiments demonstrate that this holds up in practice: the median compression ratio of 279 measured experiments is within 17% of the optimum for tree compression, and five times better than the median compression ratio of SPIN's COLLAPSE compression. Our algorithms are implemented in the LTSmin tool, and our experiments show that for model checking, multi-core tree compression pays its own way: it comes virtually without overhead compared to the fastest hash table-based methods.Comment: 19 page

Three-dimensional trajectories and network analyses of group behaviour within chimney swift flocks during approaches to the roost

Chimney swifts (Chaetura pelagica) are highly manoeuvrable birds notable for roosting overnight in chimneys, in groups of hundreds or thousands of birds, before and during their autumn migration. At dusk, birds gather in large numbers from surrounding areas near a roost site. The whole flock then employs an orderly, but dynamic, circling approach pattern before rapidly entering a small aperture en masse. We recorded the three-dimensional trajectories of ≈1 800 individual birds during a 30 min period encompassing flock formation, circling, and landing, and used these trajectories to test several hypotheses relating to flock or group behaviour. Specifically, we investigated whether the swifts use local interaction rules based on topological distance (e.g. the n nearest neighbours, regardless of their distance) rather than physical distance (e.g. neighbours within x m, regardless of number) to guide interactions, whether the chimney entry zone is more or less cooperative than the surrounding flock, and whether the characteristic subgroup size is constant or varies with flock density. We found that the swift flock is structured around local rules based on physical distance, that subgroup size increases with density, and that there exist regions of the flock that are less cooperative than others, in particular the chimney entry zone