57,281 research outputs found
Geochronology of the Damara Orogen — A Review
No full textA review of the geochronological literature on the Damara Orogen indicates an extended period of deposition on a rifting and stretching continental crust lasting several hundred million years until about 600 Ma ago. This relatively quiet period was followed by a second phase of rapid comression, crustal thickening, uplift, metamorphism and very voluminous granite intrusions between 550 and 510 Ma ago. The peak of regional metamorphism seems to have occurred around 530 Ma ago over the whole width of the orogen. An area of granites of relatively young Pb/Sr ages (around 470 Ma) exists in the northern Central Zone of the orogen
Geologische Specialkarte von Preussen und den Thüringischen Staaten / 6923 Tann
No full textgeologisch bearbeitet durch W. Haack 1909 u. 191
Programma De Libertate Sentiendi Non Libera. Quo Ad Dissertationem Inauguralem De Iure Apostillae Seu Postscripti, A Clarissimo Candidato Ioanni Daniele Haakio, Nordlinga-Suevo, Habendam, Iurisprudentiae Cultores Invitat Ioannes Samuel Strykius, D. Prof. P. Ord. Et Fac. Iurid. H.T. Decanus
No full textEinladungsschrift zur jur. Promotion von Johann Daniel Haack, 18. Mai 1702Halle/Saale, Univ., Programm, 1702Nicht identisch mit VD18 15182355, abweichende Schreibweisen u/v und z.B. Io. statt IoanniSignaturformel: G4Erscheinungsjahr nach der Datierung am Schluß bestimm
Arno J. Haack to U. S. Embassy, London, England, Decemebr 20 1967
No full textInquiry for the status of Sharma's visa applicationLetter accompanying the copy of message to embassyCorrespondenc
The isotopic composition of anthropogenic Pb in soil profiles of northern Germany: Evidence for pollutant Pb from a continent-wide mixing system
No full textSeventy-five samples of six soil profiles from forests on different substrates plus one next to a motorway were analyzed for the variation of Pb concentration and isotopic composition with depth. A substantial fraction of the anthropogenic Pb (peak concentrations between 74 and 300 ppm) is still stored in the organic top soil, and seldom penetrates deeper than 20-30 cm. In (Pb-208/Pb-206) vs. (Pb-207/Pb-206)-diagrams the Pb in the uppermost layers of the profiles plots on an excellent correlation line (R = 0.99) indicating essentially a two-component mixing system. Values for the dust on Scottish plants, Norwegian and Swiss bogs as well as for aerosols collected over the North Atlantic (data from the literature) plot on the same correlation line showing that the Pb was deposited from a continent-wide mixing system with two apparent end members: The radiogenic one is similar to geogenic Pb and could consist of contributions from certain European ore deposits and from different soil components (e.g. silicates and Fe-oxides), power plants and cement factories. The less radiogenic component must contain or consist of Pb from Proterozoic or even Archaic ore deposits. However, the sources of this Pb remain somewhat elusive. In any case, this isotopic pattern is so consistent all over Europe that the correlation line may serve as a line of reference for quasi normal or European Standard Lead Pollution (ESLP). The gasoline derived Pb in the soils is swamped by Pb of other provenances
On the isotopic composition of Pb in cloud waters in Central Germany. A source discrimination study
No full textFifty seven (57) cloud water samples collected in 1 hr intervals during 9 cloud events in 1997 at the summit of the Brocken (altitude 1142 m) in Central Germany were analyzed for their Pb concentrations and isotopic compositions. For comparison, filter dusts of such possible emitters as power plants, cement factories, waste incinerators, cars and others were also studied. Profiles over many hours reveal changes in composition correlated with changes in the origin of the air masses. Five main groups of possible sources of the Pb can be distinguished: most important are (1) the European standard pollution ESP dominating the continent from Germany over France to Scandinavia and (2) industrial Pb (and soot from car exhausts) followed by (3) urban waste incinerators as well as (4) perhaps ores from Norilsk/Siberia, and, somewhat uncertain, (5) ores from Paleozoic European deposits. Local and daily varying anthropogenic emissions of the sources (2-5) cause scatter of the points around the ESP correlation line. In soils all these variations and individual signatures are levelled out so that specific sources of pollution cannot be identified anymore. Geogenic Pb from rocks and soils is the same as that from power plants and cement factories. It is one of the two nominal end components making up the mixture of the ESP. The less radiogenic end component of this mix which must contain Pb from very old deposits is somewhat elusive: none of the large Archaic or Proterozoic deposits could be identified. Most probably numerous sources contribute to this Pb. Pb from leaded gasoline seems to be absent or is hidden under the five components dominating the composition of the Pb in the European environment. This probably reflects phasing out of such gasoline in most European countries. The Pb in the clouds may contain a small component of old Proterozoic or even Archaic Pb, but it can also be modelled with Paleozoic Pb
A Dynamic Subfilter-scale Stress Model for Large Eddy Simulations Based on Physical Flow Scales
No full textWe propose a new definition of the length scale in an eddy-viscosity model for large-eddy simulations (LES). This formulation extends and generalizes a previous proposal [Piomelli, Rouhi and Geurts, Proc. ETMM10, 2014], in which the LES length scale was expressed in terms of the integral length-scale of turbulence determined by the flow characteristics and explicitly decoupled from the simulation grid; this approach was named Integral Length-Scale Approximation (ILSA). As in the original ILSA, the model coefficient was determined by the user, and required to maintain a desired contribution of the unresolved, subfilter scales (SFS) to the global transport. We propose a local formulation (local ILSA) in which the model coefficient is local in space, allowing a precise control over SFS activity as a function of location. This new formulation preserves the properties of the global model; application to channel flow and backward-facing step verifies its features and accuracy
Large-eddy simulation of a separated flow with a sub-filter scale model based on the integral length-scale
No full textA new sub-filter scale model for large-eddy simulations, which uses a length-scale proportional to the integral scale of the turbulence instead of the grid resolution to parametrize the modelled stresses, will be assessed in the prediction of the flow of a boundary-layer over a rough surface, which includes separation and reattachment
Near Wall PIV-Measurements on the Windward Slope of a Hill
No full textThe turbulent flow over periodic hills was measured near to the wall, using planar Particle-Image-Velocimetry (PIV) at high spatial resolution. Our focus is on the near wall turbulence structure on the windward slope of the hill. For large-eddy simulation (LES) we suspect that, if this was not predicted accurately, it affects the prediction of the velocity profiles over the hill crest which in turn will affect the recirculation length downstream of the hill. Regarding the time averaged velocities, we were able to resolve the linear viscous region of the boundary layer. The velocity distribution and also the Reynolds stress does not comply with the law of the wall as it is valid for a turbulent boundary layer at equilibrium
Energy dissipation and flux laws for unsteady turbulence
No full textDirect Numerical Simulations of spatially periodic unsteady turbulence show that the high Reynolds number scalings of the instantaneous energy dissipation rate and interscale energy flux at intermediate wavenumbers are qualitatively different from the well-known cornerstone scalings of equilibrium turbulence where and are time-dependent rms velocity and integral length-scales. Instead, they both scale as where and are length and velocity scales characterizing initial/overall unsteady turbulence conditions
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