Explicit modeling of composite plates and beams in the dynamics of multibody systems

The state of the art dynamic response analysis of flexible multibody systems is currently restricted to elastic bodies with homogeneous materials. The requirements for high speed operation has made it necessary to use lightweight multi layered composite bodies in robotic systems and space structure applications. Dynamic modeling and analysis of such systems are particularly important since the effects of body flexibility to the performance are likely to be more pronounced. The eight-noded isoperimetric quadrilateral element with independent rotational and displacement degrees of freedom is extended to laminated composite elements. The element includes an arbitrary number of bonded layers, each of which may have a different thickness. The transverse shear deformation which is a predominant factor in the analysis of laminated composite structures is taken into account in developing the stiffness and mass matrices. The corresponding 3-D mode shapes are then incorporated to the multibody system dynamical equations. Floating body reference frames allow the selection of different boundary conditions, and the dynamical equations contain all the nonlinear interactions between the rigid and elastic motion. Example simulations are presented to illustrate the methods proposed

HYDROGEN IN Fe80B20 AND Fe40Ni40P14B6 AMORPHOUS ALLOYS

L'effet de l'hydrogène et/ou de la déformation sur le frottement interne, le trainage magnétique et le temps de vie des positons dans les alliages amorphes est étudié de 4 à 400 K. On observe vers 200 K un pic de frottement interne et vers 150 K la relaxation magnétique correspondante. Après recuit à 340 K, une augmentation transitoire de l'amplitude est observée. Ceci indiquerait un mécanisme d'interaction : "nuage d'hydrogène / quasi dipole de dislocations".The effect of hydrogen and/or deformation on internal friction, magnetic after effect, and positron lifetime in amorphous alloys is investigated between 4 and 400 K. In hydrogen charged and cold worked + hydrogen charged specimens, an internal friction peak is found around 200 K and a corresponding magnetic after effect around 150 K. After aging at 340 K, transient peak enhancements are observed. An explanation in terms of "hydrogen-dislocation dipole like" interaction is given

Systematics of alpha decay half-lives within the position-dependent mass formalism

In this paper, we present a new study about $$\alpha$$ decay process in the framework of the quantum concept, namely: the position dependent mass formalism. Such a study allowed us to obtain a new generalized formula for $$\alpha$$ decay half-lives which enables us to rebuild the majority of the formulas existing in the literature. Moreover, from this generalized formula, we derived two new practical ones. We have tested these two latter on 397 nuclei ($$52<Z<118$$). By comparing our obtained results with those from the majority of semi-empirical formulas in the literature, it comes out that one of these two new proposed formulas is the most precise one inasmuch as it presents the lowest r.m.s deviation in respect to the experimental data particularly for even–even nuclei. Based on this new formula, we make predictions for some super-heavy nuclei

Isotopic and Isotonic Evolution of the Symmetry Energy and Skins of Mirror Nuclei

11 pags., 5 figs., 2 tabs.The knowledge of the neutron skin is important for nuclear physics and astrophysics, but its experimental determination faces many challenges. We calculate the neutron skin of a nucleus by using the possibility to relate it with the difference between the proton radii of the corresponding mirror nuclei as an alternative way. The calculations are based on the Hartree-Fock-Bogoliubov method by using the cylindrical transformed deformed harmonic oscillator basis. Predictions for proton skins are also made for several mirror pairs in the middle mass range. The correlation between the thickness of the neutron skin and the characteristics related with the density dependence of the nuclear symmetry energy is investigated for Ni isotopic chain with mass number A = 48 ¿ 60 and the respective mirror nuclei. These quantities are calculated within the coherent density fluctuation model using Brueckner and Skyrme energy-density functionals for isospin asymmetric nuclear matter with two Skyrme-type effective interactions, SkM* and SLy4. Results are also presented for the symmetry energy as a function of A for a family of mirror pairs from selected chains of nuclei with Z=20, N=14, and N=50. The evolution curves show a similar behavior crossing at the double-magic nucleus in each chain and a smooth growing deviation when N 6= Z starts. Comparison of our results for the radii and skins with those from the calculations based on high-precision chiral forces is made.This work was partially supported by the Bulgarian National Science Fund under Contract No. KP-06-N38/1

Preparation and thermal properties of organically modified bentonite with ionic liquids

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Complete genome sequence and description of Lactococcus garvieae M14 isolated from Algerian fermented milk

We describe using a polyphasic approach that combines proteomic by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF) analysis, genomic data and phenotypic characterization the features of Lactococcus garvieae strain M14 newly isolated from the fermented milk (known as raib) of an Algerian cow. The 2 188 835 bp containing genome sequence displays a metabolic capacity to form acid fermentation that is very useful for industrial applications and encodes for two bacteriocins responsible for its eventual bioprotective properties