316 research outputs found

    Review of the New World genera of the Leafhopper Tribe Erythroneurini (Hemiptera: Cicadellidae: Typhlocycbinae)

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    The genus-level classification of New World Erythroneurini is revised based on results of a phylogenetic analysis of 100 morphological characters. The 704 known species are placed into 18 genera. Erasmoneura Young and Eratoneura Young, previously treated as subgenera of Erythroneura Fitch, and Erythridula Young, most recently treated as a subgenus of Arboridia Zachvatkin, are elevated to generic status. Three species previously included in Erasmoneura are placed in a new genus, Rossmoneura (type species, Erythroneura tecta McAtee). The concept of Erythroneura is thereby narrowed to include only those species previously included in the nominotypical subgenus. New World species previously included in Zygina Fieber are not closely related to the European type species of that genus and are therefore placed in new genera. Neozygina, n. gen., based on type species Erythroneura ceonothana Beamer, includes all species previously included in the ???ceonothana group???, and Zyginama, n. gen., based on type species Erythroneura ritana Beamer, includes most species previously included in the ???ritana group??? of New World Zygina. Five additional new genera are described to include other previously described North American Erythroneurini: Hepzygina, n. gen., based on type species Erythroneura milleri Beamer and also including E. aprica McAtee; Mexigina, n. gen., based on type species Erythroneura oculata McAtee; Nelionidia, n. gen., based on type species N. pueblensis, n. sp., three additional new species, and Erythroneura amicis Ross; Neoimbecilla, n. gen., based on type species Erythroneura kiperi Beamer and one new species; and Illinigina, n. gen., based on type species Erythroneura illinoiensis Gillette. Five new genera, based on previously undescribed species, are also recognized: Aztegina, n. gen, based on A. punctinota, n. sp., from Mexico; Amazygina, n. gen., based on type species A. decaspina, n. sp., and three additional new species from Ecuador; Hamagina, n. gen., based on type species H. spinigera, n. sp., and two additional new species from Peru and Ecuador; Napogina, n. gen., based on type species N. recta, n. sp., and one additional new species from Ecuador; Perugina, n. gen., based on type species P. denticula, n. sp., from Peru; and Spinigina, n. gen., based on type species S. hirsuta, n. sp., and an additional new species from Peru. Phylogenetic analysis suggests that the New World Erythroneurini consist of three lineages resulting from separate invasions from the Old World.published or submitted for publicationis peer reviewe

    Translationally invariant nonlinear Schrodinger lattices

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    Persistence of stationary and traveling single-humped localized solutions in the spatial discretizations of the nonlinear Schrodinger (NLS) equation is addressed. The discrete NLS equation with the most general cubic polynomial function is considered. Constraints on the nonlinear function are found from the condition that the second-order difference equation for stationary solutions can be reduced to the first-order difference map. The discrete NLS equation with such an exceptional nonlinear function is shown to have a conserved momentum but admits no standard Hamiltonian structure. It is proved that the reduction to the first-order difference map gives a sufficient condition for existence of translationally invariant single-humped stationary solutions and a necessary condition for existence of single-humped traveling solutions. Other constraints on the nonlinear function are found from the condition that the differential advance-delay equation for traveling solutions admits a reduction to an integrable normal form given by a third-order differential equation. This reduction also gives a necessary condition for existence of single-humped traveling solutions. The nonlinear function which admits both reductions defines a two-parameter family of discrete NLS equations which generalizes the integrable Ablowitz--Ladik lattice.Comment: 24 pages, 4 figure

    Technology of 3D Simulation of High-Speed Damping Processes in the Hydraulic Brake Device

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    This chapter describes a three-dimensional simulation technology for physical processes in concentric hydraulic brakes with a throttling-groove partly filled hydraulic cylinder. The technology is based on the numerical solution of a system of Navier–Stokes equations. Free surface tracking is provided by the volume of fluid (VOF) method. Recoiling parts are simulated by means of moving transformable grids. Numerical solution of the equations is based on the finite-volume discretization on an unstructured grid. Our technology enables simulations of the whole working cycle of the hydraulic brake. Results of hydraulic brake simulations in the counter-recoil regime are reported. The results of the simulations are compared with experimental data obtained on JSC “KBP” test benches. The calculated and the experimental sets of data are compared based on the piston velocity as a function of distance. The performance of the hydraulic brake is studied as a function of the fluid mass and firing elevation of the gun

    Raman scattering of InAs/AlAs quantum dot superlattices grown on (001) and (311)B GaAs surfaces

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    We present a comparative analysis of Raman scattering by acoustic and optical phonons in InAs/AlAs quantum dot superlattices grown on (001) and (311)B GaAs surfaces. Doublets of folded longitudinal acoustic phonons up to the fifth order were observed in the Raman spectra of (001)- and (311)B-oriented quantum dot superlattices measured in polarized scattering geometries. The energy positions of the folded acoustic phonons are well described by the elastic continuum model. Besides the acoustic phonons, the spectra display features related to confined transverse and longitudinal optical as well as interface phonons in quantum dots and spacer layers. Their frequency positions are discussed in terms of phonon confinement, elastic stress, and atomic intermixing

    Calculation of fire resistance of building structures in software packages

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    In the article a review of modern software systems allowing calculating the distribution of temperature fields in a structure in time, without loading and with it (the fire resistance limit of structures) under conditions of a special fire load has been given. The algorithm of the finite element method is used for the calculations, on which each of the considered complexes is based. Specifically: Sofistik, Abaqus, Normcad, Ansys, Robot structure. Comparative analysis has been made from the point of view of intuitive user interface, the possibilities of modeling various conditions and fire regimes, tools for communication with other software complexes and the format of output of results. The results demonstrating the capabilities of the post-processor Sofistik have been presented

    Elastic properties of fullerites and diamond-like phases

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    Diamond‐like structures, that include sp2 and sp3 hybridized carbon atoms, are of considerable interest nowadays. In the present work, various carbon auxetic structures are studied by the combination of molecular dynamics (MD) and analytical approach. Two fullerites based on the fullerene C60 and fullerene‐like molecule C48 are investigated as well as diamond‐like structures based on other fullerene‐like molecules (called fulleranes), carbon nanotubes (called tubulanes) and graphene sheets. MD is used to find the equilibrium states of the structures and calculate compliance and stiffness coefficients for stable configurations. Analytical methods are used to calculate the engineering elastic coefficients (Young's modulus, Poisson's ratio, shear modulus and bulk modulus), and to study their transformation under rotation of the coordinate system. All the considered structures are partial auxetics with the negative value of Poisson's ratio for properly chosen tensile directions. It is shown that some of these structures, in a particular tension direction, have a very high Young's modulus, that is, 1852 GPa for tubulane TA6
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