An early Tournaisian (Mississippian) bryozoan fauna from the Moravian Karst (Rhenohercynian Zone, Czech Republic)

© 2017 Bryozoans are described from the lower Tournaisian of the Moravo-Silesian Zone (part of the Rhenohercynian Zone) of the Czech Republic for the first time. The studied fauna displays poor diversity and small size; it is represented by encrusting unilaminar and delicate branching growth habits. One species, Eridopora moravica, is new, and three other species are left in open nomenclature: Nikiforovella sp., Saffordotaxis sp., and ?Streblotrypella sp. Bryozoans found within calciturbidites of the Siphonodella sulcata and Siphonodella quadruplicata conodont zones inhabited originally the littoral zone at the southern margin of Laurussia. They indicate links between the eastern and western parts of the northern Palaeotethyan Siberian and Panthalassan realms

Electronic structure of GdN, and the influence of exact exchange

GdN bulk is studied with the local density approximation, on the Hartree-Fock level, and on the level of the hybrid functional B3LYP. A local basis set formalism is used, as implemented in the present CRYSTAL06 release. It is demonstrated that the code is technically capable of treating this system with its 4f electrons explicitly, i.e. out of the core. The band structure at the level of the local density approximation is in good agreement with earlier calculations and is found to be half-metallic. The Hartree-Fock band structure is insulating with a large gap. Interestingly, three solutions were found at the B3LYP level. The lowest of them is insulating for majority spin, and the Fermi surface for minority spin consists only of points, resulting in a very low density of states around the Fermi level.Comment: to appear in J. Phys.: Condensed Matte

Influence of electron correlations on ground-state properties of III-V semiconductors

Lattice constants and bulk moduli of eleven cubic III-V semiconductors are calculated using an ab initio scheme. Correlation contributions of the valence electrons, in particular, are determined using increments for localized bonds and for pairs and triples of such bonds; individual increments, in turn, are evaluated using the coupled cluster approach with single and double excitations. Core-valence correlation is taken into account by means of a core polarization potential. Combining the results at the correlated level with corresponding Hartree-Fock data, we obtain lattice constants which agree with experiment within an average error of -0.2%; bulk moduli are accurate to +4%. We discuss in detail the influence of the various correlation contributions on lattice constants and bulk moduli.Comment: 4 pages, Latex, no figures, Phys. Rev. B, accepte

Cutting tool tracking and recognition based on infrared and visual imaging systems using principal component analysis (PCA) and discrete wavelet transform (DWT) combined with neural networks

The implementation of computerised condition monitoring systems for the detection cutting tools’ correct installation and fault diagnosis is of a high importance in modern manufacturing industries. The primary function of a condition monitoring system is to check the existence of the tool before starting any machining process and ensure its health during operation. The aim of this study is to assess the detection of the existence of the tool in the spindle and its health (i.e. normal or broken) using infrared and vision systems as a non-contact methodology. The application of Principal Component Analysis (PCA) and Discrete Wavelet Transform (DWT) combined with neural networks are investigated using both types of data in order to establish an effective and reliable novel software program for tool tracking and health recognition. Infrared and visual cameras are used to locate and track the cutting tool during the machining process using a suitable analysis and image processing algorithms. The capabilities of PCA and Discrete Wavelet Transform (DWT) combined with neural networks are investigated in recognising the tool’s condition by comparing the characteristics of the tool to those of known conditions in the training set. The experimental results have shown high performance when using the infrared data in comparison to visual images for the selected image and signal processing algorithms

Ground-state properties of rutile: electron-correlation effects

Electron-correlation effects on cohesive energy, lattice constant and bulk compressibility of rutile are calculated using an ab-initio scheme. A competition between the two groups of partially covalent Ti-O bonds is the reason that the correlation energy does not change linearly with deviations from the equilibrium geometry, but is dominated by quadratic terms instead. As a consequence, the Hartree-Fock lattice constants are close to the experimental ones, while the compressibility is strongly renormalized by electronic correlations.Comment: 1 figure to appear in Phys. Rev.

On the Chemical Origin of the Gap Bowing in (GaAs)1−xGe2x Alloys: A Combined DFT–QSGW Study

Motivated by the research and analysis of new materials for photovoltaics and by the possibility of tailoring their optical properties for improved solar energy conversion, we have focused our attention on the (GaAs)1−xGe2x series of alloys. We have investigated the structural properties of some (GaAs)1−xGe2x compounds within the local-density approximation to density-functional theory, and their optical properties within the Quasiparticle Self-consistent GW approximation. The QSGW results confirm the experimental evidence of asymmetric bandgap bowing. It is explained in terms of violations of the octet rule, as well as in terms of the order–disorder phase transition

An early Tournaisian (Mississippian) bryozoan fauna from the Moravian Karst (Rhenohercynian Zone, Czech Republic)

© 2017 Bryozoans are described from the lower Tournaisian of the Moravo-Silesian Zone (part of the Rhenohercynian Zone) of the Czech Republic for the first time. The studied fauna displays poor diversity and small size; it is represented by encrusting unilaminar and delicate branching growth habits. One species, Eridopora moravica, is new, and three other species are left in open nomenclature: Nikiforovella sp., Saffordotaxis sp., and ?Streblotrypella sp. Bryozoans found within calciturbidites of the Siphonodella sulcata and Siphonodella quadruplicata conodont zones inhabited originally the littoral zone at the southern margin of Laurussia. They indicate links between the eastern and western parts of the northern Palaeotethyan Siberian and Panthalassan realms

An early Tournaisian (Mississippian) bryozoan fauna from the Moravian Karst (Rhenohercynian Zone, Czech Republic)

© 2017 Bryozoans are described from the lower Tournaisian of the Moravo-Silesian Zone (part of the Rhenohercynian Zone) of the Czech Republic for the first time. The studied fauna displays poor diversity and small size; it is represented by encrusting unilaminar and delicate branching growth habits. One species, Eridopora moravica, is new, and three other species are left in open nomenclature: Nikiforovella sp., Saffordotaxis sp., and ?Streblotrypella sp. Bryozoans found within calciturbidites of the Siphonodella sulcata and Siphonodella quadruplicata conodont zones inhabited originally the littoral zone at the southern margin of Laurussia. They indicate links between the eastern and western parts of the northern Palaeotethyan Siberian and Panthalassan realms