101,923 research outputs found
Magnetic properties and 57Fe Mössbauer spectroscopy of Mediterranean prehistoric obsidians for provenance studies
No full textSamples from the Mediterranean source-islands: Gyali, Lipari, Melos, Palmarola, Pantelleria and Sardinia (Monte Arci) had their 57Fe M€ossbauer spectra and magnetizations measured. The saturation magnetization (Ms) depends on the island of provenance and it reaches a maximum 0.3 emu/g for Palmarola obsidians, indicating a larger magnetic phase content. The coercive forces (Hc) range from 46 to 372 Oe for respectively samples from Pantelleria and
Palmarola islands. Our analyses show that in a Mr=Ms vs. Hc=Hm plot the data points accumulate in areas that depend on obsidian provenance (Mr, remanent magnetization; Hm, maximum applied field). The M€ossbauer spectra are mainly
composed of broad asymmetric doublets, which were fitted assuming two Fe2þ and one Fe3þ sites. In addition, the
obsidians of Melos and Palmarola present a magnetic component attributed to magnetite and/or hematite. Binary diagrams comparing different Mossbauer hyperfine parameters for the Fe3þ and Fe2þ species gave indications of similarities and differences between obsidians of different origins. Since this kind of plot does not give an unambiguous characterization of samples from each island, a detailed analysis of the M€ossbauer results is in progress using statistical method of clustering analysis as has been shown by Scorzelli et al. [Comptes Rendus Acad. Sci., Serie II, 332 (2001) 769] and Poupeau et al. [IAOS Bull. 28 (2001) 2] in previous studies
Parallel solid modeling using BSP dataflow
No full textWe introduce a parallel approach to geometric modeling of complex objects and scenes, combining a dataflow streaming of BSP trees with a partition of the object space into independent portions, to be evaluated in parallel with minimal interprocess communication. Binary Space Partition (BSP) is a space index used in graphics for hidden-surface removal and animation. We use BSP trees with fuzzy leaves as a progressive representation of solid meshes. Our approach is implemented as a dataflow with processes that progress concurrently, where each refinement of the input to a process is mapped instantly to a refinement of the output, so that the result is also a stream of progressive refinements. This framework allows for progressive generation of complex geometric parts and large-scale assemblies. We have adapted several graphics techniques, including BSP, boundary polygons, CSG, splines and subdivision methods, to fit into our dataflow graph, where four types of processes produce, transform, combineor consume mesh cells. This approach is scalable over different kinds of HPC hardware and different number of computing nodes, by way of the decomposition of the object space and of the distribution of computational processes. Compiling a generative geometric expression into a dataflow graph is well suited to SMP machines, whereas a space decomposition into independent portions fits well with computing clusters and grids
Mechanistic Aspects of the Asymmetric Transfer Hydrogenation in the Manufacture of Noradrenaline
No full textMechanistic, stereochemical and stereoelectronic aspects of the asymmetric reduction (via hydrogen or transfer hydrogenation) for the manufacture of N-benzyl-noradrenaline from the ketone precursor are studied through catalyst screening and computational evaluations. This reaction provides an efficient and industrially suitable method for the manufacture of enantiomerically pure noradrenaline, an important neurotransmitter which is widely used as a pharmacological substance due to its sympathomimetic properties. © 2022 Wiley-VCH GmbH
Spatial Multi-criteria Analysis for Identifying Suitable Locations for Green Hydrogen Infrastructure
No full textThe paper proposes a Spatial Multi-Criteria Analysis for identifying suitable locations for green hydrogen infrastructure. The production and use of hydrogen as a renewable energy carrier can play a critical role in reducing carbon footprint and increasing energy security in cities worldwide. The approach considers multiple criteria, such as demand, accessibility, environmental impact, and cost, to identify optimal locations for hydrogen production, storage, and distribution facilities. The GIS component enables spatial analysis, allowing visualization and analysis of spatial relationships between potential locations and other relevant factors. The research claims that green hydrogen can significantly improve energy resilience and transform energy systems. The method is applied to a case study, an energy-intensive industry in the city of Potenza (Italy). The result is the map identifying suitable areas where hydrogen production facilities can be located. The approach suggests that urban planners, decision-makers, and stakeholders develop and use green hydrogen as a sustainable energy source
Progressive Conversion from B-rep to BSP for Streaming Geometric Modeling
No full textWe introduce a novel progressive approach to generate a Binary Space Partition (BSP ) and convex cell decomposition from any input triangles boundary representation (B-rep), by utilizing a very fast computation of the surface inertia. A solid model is so generated at progressive levels of detail. Thi
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