Efficient and scalable omniscient debugging for model transformations

This paper discusses a technique for supporting omniscient debugging for model transformations, which are used to define core operations on software and system models. Similar to software systems developed using general-purpose languages, model transformations are also subject to human error and may possess defects. Existing model-driven engineering tools provide stepwise execution to aid developers in locating and removing defects. In this paper, we describe our investigation into a technique and associated algorithms that support omniscient debugging features for model transformations. Omniscient debugging enables enhanced navigation and exploration features during a debugging session beyond those possible in a strictly stepwise execution environment. Finally, the execution time performance is comparatively evaluated against stepwise execution, and the scalability (in terms of memory usage) is empirically investigated.     

Influence of Temperature on the Dynamic Tensile Behavior of Zirconium

The influence of temperature on the dynamic tensile behavior of Zr has been investigated. Bullet-shaped Zr samples with two different textures were dynamically extruded at room temperature and 523 K (250 °C). A higher ductility was measured for samples deformed at elevated temperature as compared to those extruded at room temperature. This difference in ductility is discussed in terms of zirconium’s ability to accommodate plastic deformation via thermally enhanced slip activity, as evidenced by examination of the deformed microstructures.     

Inelastic Neutron Scattering and Density Functional Theory–Molecular Dynamics Study of Si Dynamics in Ti3SiC2

Observed differences between measured and calculated elastic constants for Ti₃SiC₂ are investigated using Density Functional Theory and Inelastic Neutron Scattering. The agreement between the calculated lattice dynamics and the dynamics measured by inelastic neutron scattering is considered good except at energies below ~20 meV where discrepancies suggest anharmonic potentials. This suggestion is confirmed by Density Functional Theory—Molecular Dynamics simulation which shows multiple site occupancy of the Si atoms within the basal plane at finite temperature and produces a calculated inelastic spectrum in better agreement with the measured spectrum in the low‐energy region. The highly anharmonic potential energy surface of the Si atoms offers an explanation for the failure of elastic constants, calculated based on the harmonic approximation, to agree with initial experimental measurements.     

Forensically Robust Detection of the Presence of Morpholine in Apples—Proof of Principle

Morpholine is a precursor of carcinogenic nitrosamines and although the possibility of their formation in the human stomach after ingestion of morpholine-treated apples is reported as highly unlikely morpholine has not been authorised as a food additive in the EU. Methods for its detection are required since it is permitted in other jurisdictions and may be present on food through direct treatment of fruit with waxes containing the compound, through steam treatment during processing or from packaging. Methods using derivatising agents with the inclusion of UV chromophores such as dansyl chloride yield good separation and high sensitivity but with mass spectrometric fragment ions predominantly originated from the derivatising group rather than the morpholine moiety. An amine acetylation derivatisation method is proposed from which fragment ions originating from the morpholine group are detected using widely available GC–MS. With full validation, a forensically robust confirmation of the presence of morpholine via its N-acetyl derivative is possible in support of regulatory analysis.