Relativistic dissipative hydrodynamics in the 3+1 formulation

The equations governing dissipative relativistic hydrodynamics are formulated within the 3+1 approach. Dissipation is accounted for by applying the theory of extended causal thermodynamics (Israel-Stewart theory). This description eliminates the causality violating infinite signal speeds present in the conventional Navier-Stokes equation. (orig.)SIGLEAvailable from TIB Hannover: RR 1606(98-34) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

Deformation of oriented polypropylene Proceedings

Using push-pull processing it is possible to produce oriented polypropylene in injection molding. The orientation can be visualized using X-ray diffraction (WAXD, SAXS) and Raman-Spectroscopy techniques as well as investigations using light and electron microscopy (SEM, TEM). These techniques show that an orientation both in the amorphous and crystalline phase is present. On nanoscale an orientation of lamellae perpendicular to the flow direction can be observed. Results for DSC measurements and micro-hardness over the cross-section of injection-molded plates accompany the microscopical investigations. This distinct structure has been deformed under tensile and shear load. The results show, both on macroscopic and microscopic level differences on loads parallel and perpendicular to the lamellae and in shear mode. The results are discussed by mechanical tests and microscopic investigations. The deformation on structural level shows a fibrillar, crazed structure that is examined using SEM and plasma etching preparation techniques. (orig.)Available from TIB Hannover / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

3+1 formulation of non-ideal hydrodynamics

The equations governing dissipative relativistic hydrodynamics are formulated within the 3+1 approach for arbitrary spacetimes. Dissipation is accounted for by applying theory of extended causal thermodynamics (Israel-Stewart theory). This description eliminates the causality violating infinite signal speeds present in the conventional Navier-Stokes equation. As an example we treat the astrophysically relevant case of stationary and axisymmetric spacetimes, including the Kerr metric. The equations take a simpler form whenever the inertia due to the dissipative contribution can be neglected. (orig.)SIGLEAvailable from TIB Hannover: RR 1606(97-41) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

Dissipative fluid dynamics in the 3+1 formalism

Non-ideal relativistic hydrodynamics is formulated with respect to fiducial observers (FIDOs). Three types of theories for dissipative relativistic fluids are considered, which have different causality properties, and different complexity of the equations that determine the dissipative fluxes. The 3+1 equations for these fluid theories are given in terms of the three-space quantities which correspond to those familiar from non-relativistic physics. (orig.)SIGLEAvailable from TIB Hannover: RR 1606(99-05) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

A method for in situ measurement of the elastic behavior of a columnar thermal barrier coating

The mechanical behavior of a ceramic coating and the evolution of this behavior in-service play crucial roles in governing the performance and lifetime of these materials. A protocol is presented that allows for characterization of the in-plane elastic modulus and strain to failure of fragile ceramic coatings. The protocol employs digital image correlation (DIC) to measure time-resolved, full-field strain maps of bilayer microbeams, and material properties are extracted through direct comparison with finite element simulations of microbending experiments. The efficacy of the method is demonstrated by the measurement of the in-plane Young's modulus (E(TBC) = 15-30 GPa) and the strain to fracture (3.5-5 x 10(-3)) of electron beam physical vapor deposited 7% yttria-stabilized zirconia thermal barrier coatings (TBCs). The results from this study also indicate that the in-plane TBC modulus has no strain dependence when measured in tension. (C) 2011 Published by Elsevier Ltd. on behalf of Acta Materialia Inc

Current-driven instabilities in astrophysical jets: linear analysis

Current-driven instabilities of force-free screw pinches are studied for a large variety of magnetic configurations by means of a global linear analysis in an ideal MHD framework. The magnetic pitch, P=rB_z/B_#phi#, in particular its value on the axis, P_0, essentially determines the growth rate of the fastest growing kink instability and allows to identify two regimes. In the large pitch regime, representative for the majority of controlled fusion devices, the stability properties are highly sensitive to the radial pitch profile. Astrophysical jets of magnetic origin are likely to have dominantly azimuthal fields. For such configurations the properties of the fastest growing kink instability become nearly independent of the details of the pitch profile. The most unstable mode grows with an e-folding time t_g=7.52 P_0/v_A and an axial wavelength #lambda#=8.43 P_0 in the rest frame of the jet. The magnetic structure of jets with dominantly azimuthal fields will be modified by the fast growing kink instability. An analysis of the eigenfunction shows however that the kink is an internal mode which does not cause a significant sidewise displacement of the jet surface. (orig.)SIGLEAvailable from TIB Hannover: RR 1606(2000,1) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

Current-driven instabilities in astrophysical jets: non linear development

The non linear development of instabilities driven by the presence of an electric current is investigated for magnetized jets using 3-dimensional MHD simulations. General magnetic equilibria for cold supermagnetosonic jets with constant velocity are considered in order to study the influence of the initial configuration on the non linear evolution. It is found that the current density is redistributed within the inner part of the jet radius with a characteristic time scale and an axial wavelength in agreement with the linear analysis. For equilibria having a pitch profile that increases with radius, an internal helical ribbon with a high current density is forming. It gives rise to considerable dissipation which is radially localized, and may result in heating and particle acceleration within the jet. (orig.)SIGLEAvailable from TIB Hannover: RR 1606(2000,6) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman