Universtitat Stuttgart

Stuttgart, Germany

Universtitat Stuttgart

Stuttgart, Germany
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Jarrar G.H.,University of Jordan | Stern R.J.,University of Texas at Dallas | Theye T.,Universtitat Stuttgart | Yaseen N.,University of Jordan | And 5 more authors.
Lithos | Year: 2017

An Ediacaran mafic intrusion of south Jordan is a distinctive appinitic igneous rock with a possibly unique texture, characterized by spherical clots up to 40 mm in diameter composed of amphibole cores from which plagioclase euhedra radiate; we call it the Rosetta Gabbro. It is exposed as a small (ca. 750 m2) outcrop in the Neoproterozoic basement of south Jordan. A second outcrop of otherwise similar gabbro is located about 400 m to the north of the Rosetta Gabbro, but it lacks the distinctive texture. The Rosetta Gabbro could represent a magma pipe. It intrudes the Aqaba Complex (~ 600 Ma) granitoids and metasediments of the Janub Metamorphic Complex (633–617 Ma). The gabbro is an Ol- to QZ tholeiite with the following chemical characteristics: SiO2 = 46.2–47.8 wt.%; Al2O3 = 16.4–17.7 wt.%, TiO2 = 1.70–2.82 wt.%, Na2O = 1.27–2.83 wt.%. K2O = 0.82–1.63 wt.%; Mg# 58–63; Σ REE = 70–117 ppm; La/Yb ~ 6 to 8; and Eu/Eu⋆ = 1.05–1.2. The investigated gabbro has the geochemical features of a continental flood tholeiitic basalt emplaced in a within-plate tectonic setting. Two varieties of amphiboles are found: 1) large, 3–5 mm, brown ferri-titanian-tschermakite (K0.09Na0.28)(Na0.20Ca1.80)(Mn0.04Fe3 + 1.1Mg2.34Fe2 + 0.90Ti0.29Al0.22)(Al1.85Si6.15)O22(OH)1.95 of the calcic amphibole group which is riddled with opaques; and 2) acicular yellowish-light green ferrian-magnesiohornblende (K0.04Na0.153)(Ca1.755Na0.245) (Fe3 + 0.66Mn0.01Fe2 + 1.01Mg3.03Ti0.06Al0.22)(Al1.03Si6.97)O22(OH)1.95. Scattered flakes of phlogopite also occur. Tabular radiating plagioclase (An64–79) are complexly twinned, with broad lamellae that show no zoning. Laser-ablation ICP-MS analyses of amphibole and plagioclase reveal considerable variation in trace element abundance, in spite of more subtle major element variations except for TiO2 in amphibole. The REE in the amphibole shows an order of magnitude variation with a concave-downward pattern and a positive Eu anomaly Eu/Eu⋆ = 0.6–2, though far less pronounced compared to the Eu/Eu⋆ = 5–45 of plagioclase. The 3D dandelion-like texture of the rosettas is broadly similar to “Chrysanthemum Stone”, which is a diagenetic growth in sedimentary rock, but we can find no description of similar textures in igneous rocks. The formation of the rosettas is thought to reflect loss of magmatic water resulting in supersaturation of plagioclase, which grew rapidly around amphibole and may have floated in the magma. This implies magmatic evolution in shallow (10 to 12 km deep) crust where temperatures were nevertheless in the range of ca. 750 to 900 °C. © 2017 Elsevier B.V.

Koppel M.,Universtitat Stuttgart | Kroker I.,Universtitat Stuttgart | Rohde C.,Universtitat Stuttgart
Computational Geosciences | Year: 2017

We model random locations of spatial interfaces of heterogeneities in porous media by means of the hybrid stochastic Galerkin (HSG) approach. This approach extends the concept of the generalized polynomial chaos (PC) expansion for a multi-element decomposition of the multidimensional stochastic space. In this way, the physically two-dimensional hyperbolic-elliptic fractional flow formulation for two-phase flow in heterogeneous porous media is transformed from a random partial differential equation into a deterministic system for the coefficients of the PC expansion of the primary unknown saturation, total velocity, and global pressure. The hyperbolic part is discretized based on a central-upwind finite volume scheme along with a mixed finite element method for the elliptic part. The latter partly uses the tensor product structure of the saddle point system together with appropriate preconditioning to speed up the computations. Since we use the sequential implicit pressure explicit saturation (IMPES) approach, the elliptic part is solved in every time step. The proposed method is particularly well-suited for parallel computations and allows for the consideration of a huge variety of complex flow problems. We illustrate the power of the method by means of several striking numerical examples of different complexities including their numerical convergence analysis. © 2017 Springer International Publishing Switzerland

Kroker I.,Universtitat Stuttgart | Nowak W.,University of Stuttgart | Rohde C.,Universtitat Stuttgart
Computational Geosciences | Year: 2015

Simulating in flow problems in porous media often requires techniques for uncertainty quantification in order to represent parameter values that are not given exactly. Straightforward Monte-Carlo (MC) methods have a limited efficiency due to slow convergence. Better convergence in low-parametric problems can be achieved with polynomial chaos expansion (PCE) techniques. The PCE approach yields a coupled deterministic system to be solved. The degree of coupling increases with the non-linearity of the considered equations and with the order of polynomial expansion. This fact increases the computational effort of PCE and significantly reduces the scalability in parallelization. We present an application of the hybrid stochastic Galerkin finite volume (HSG-FV) method to a two-phase flow problem in two space dimensions. The method extends the classical polynomial chaos expansion by a multi-element discretization in the probability space of the parameters. It leads to a deterministic system that is coupled to a lesser degree than in element-free PCE versions, respectively, fully decoupled in stochastic elements (SE). Therefore, the HSG-FV method allows for more efficient parallelization. For the further reduction of complexity, we present a new stochastic adaptivity method. We present numerical examples in two spatial dimensions with linear and nonlinear fractional flow functions in the two-phase flow problem. The flow functions might depend in a discontinuous manner on the unknown spatial position of porous-medium heterogeneities. Finally, we discuss the interplay of the new method with spatial adaptivity per SE for these problems. © 2015, Springer International Publishing Switzerland.

Kuchler S.,Universtitat Stuttgart | Sawodny O.,Universtitat Stuttgart
At-Automatisierungstechnik | Year: 2011

Compensation of vertical vessel motion is a common control task in the field of ocean engineering. Such compensation systems can be realized with trajectory tracking controllers. To plan the trajectories online, a short-time prediction of the vertical vessel motion is advantageously, since actuator constraints can be taken into account more efficiently. This article proposes an observer-based method for a short-time prediction. © Oldenbourg Wissenschaftsverlag.

Srama R.,Max Planck Institute for Nuclear Physics | Srama R.,Universtitat Stuttgart | Kempf S.,Universtitat Braunschweig | Kempf S.,Universtitat Colorado | And 48 more authors.
CEAS Space Journal | Year: 2011

The interplanetary space probe Cassini/Huygens reached Saturn in July 2004 after 7 years of cruise phase. The German cosmic dust analyser (CDA) was developed under the leadership of the Max Planck Institute for Nuclear Physics in Heidelberg under the support of the DLR e. V. This instrument measures the interplanetary, interstellar and planetary dust in our solar system since 1999 and provided unique discoveries. In 1999, CDA detected interstellar dust in the inner solar system followed by the detection of electrical charges of interplanetary dust grains during the cruise phase between Earth and Jupiter. The instrument determined the composition of interplanetary dust and the nanometre-sized dust streams originating from Jupiter's moon Io. During the approach to Saturn in 2004, similar streams of submicron grains with speeds in the order of 100 km/s were detected from Saturn's inner and outer ring system and are released to the interplanetary magnetic field. Since 2004 CDA measured more than one million dust impacts characterising the dust environment of Saturn. The instrument is one of the three experiments which discovered the active ice geysers located at the south pole of Saturn's moon Enceladus in 2005. Later, a detailed compositional analysis of the water ice grains in Saturn's E ring system led to the discovery of large reservoirs of liquid water (oceans) below the icy crust of Enceladus. Finally, the determination of the dust-magnetosphere interaction and the discovery of the extended E ring (at least twice as large as predicted) allowed the definition of a dynamical dust model of Saturn's E ring describing the observed properties. This paper summarizes the discoveries of a 10-year story of success based on reliable measurements with the most advanced dust detector flown in space until today. This paper focuses on cruise results and findings achieved at Saturn with a focus on flux and density measurements. CDA discoveries related to the detailed dust stream dynamics, E ring dynamics, its vertical profile and E ring compositional analysis are published elsewhere (see Hus et al. in AIP Conference Proccedings 1216:510-513, 2010; Hsu et al. in Icarus 206:653-661, 2010; Kempf et al. in Icarus 193:420, 2008; 206(2):446, 2010; Postberg et al. in Icarus 193(2):438, 2008; Nature 459:1098, 2009; Nature, 2011, doi:10.1038/nature10175). © 2011 CEAS.

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