Geoenergy: new concepts for utilization of geo-reservoirs as potential energy sources     

Magdalena Scheck-Wenderoth  Dieter Schmeißer  Maria Mutti  Olaf Kolditz  Ernst Huenges  Hans-Martin Schultz  Axel Liebscher  Michaela Bock 《Environmental Earth Sciences》2013,70(8):3427-3431

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Dynamo models with magnetic diffusivity-quenching     

G. Rüdiger  L. L. Kitchatinov  M. Küker  M. Schultz 《地球物理与天体物理流体动力学》2013,107(1-4):247-259

Abstract

The magnetic influence on a turbulent plasma also produces a complicated structure of the eddy diffusivity tensor rather than a simple and traditional quenching of the eddy diffusivity. Dynamo models in plane (galaxy) and spherical (star) geometries with differential relation are developed here to answer the question whether the dynamo mechanism is still yielding stable configurations. Magnetic saturation of the dynamos is always found—at magnetic energies exceeding the energy-equipartition value.

We find that the effect of magnetic back-reaction on the turbulent diffusivity depends highly on whether the dynamo is oscillatory or not. The steady modes are extremely influenced. They saturate at field strengths strongly exceeding its turbulence-equipartition value. Subcritical excitation is even found for strong seed fields. The oscillating dynamos, however, only provide a small effect. Hence, the strong over-equipartition of the internal solar magnetic fields revealed by studies of flux-tube dynamics cannot be explained with the theory presented. Also the run of the cycle frequency with the dynamo number is too smooth in order to explain observations of stellar chromospheric activity.  相似文献   

Simulating Gravity Changes in Topologically Realistic Driven Earthquake Fault Systems: First Results     

Kasey W. Schultz  Michael K. Sachs  Eric M. Heien  John B. Rundle  Don L. Turcotte  Andrea Donnellan 《Pure and Applied Geophysics》2016,173(3):827-838

Currently, GPS and InSAR measurements are used to monitor deformation produced by slip on earthquake faults. It has been suggested that another method to accomplish many of the same objectives would be through satellite-based gravity measurements. The Gravity Recovery and Climate Experiment (GRACE) mission has shown that it is possible to make detailed gravity measurements from space for climate dynamics and other purposes. To build the groundwork for a more advanced satellite-based gravity survey, we must estimate the level of accuracy needed for precise estimation of fault slip in earthquakes. We turn to numerical simulations of earthquake fault systems and use these to estimate gravity changes. The current generation of Virtual California (VC) simulates faults of any orientation, dip, and rake. In this work, we discuss these computations and the implications they have for accuracies needed for a dedicated gravity monitoring mission. Preliminary results are in agreement with previous results calculated from an older and simpler version of VC. Computed gravity changes are in the range of tens of μGal over distances up to a few hundred kilometers, near the detection threshold for GRACE.  相似文献   

Leaching of viruses and other microorganisms naturally occurring in pig slurry to tile drains on a well-structured loamy field in Denmark     

Jesper S. Krog  Anita Forslund  Lars E. Larsen  Anders Dalsgaard  Jeanne Kjaer  Preben Olsen  Anna Charlotte Schultz 《Hydrogeology Journal》2017,25(4):1045-1062

The amount of animal manure used in modern agriculture is increasing due to the increase in global animal production. Pig slurry is known to contain zoonotic bacteria such as E. coli, Salmonella spp. and Campylobacter spp., and viruses such as hepatitis E virus and group A rotavirus. Coliform bacteria, present in manure, have previously been shown to leach into tile drains. This poses a potential threat to aquatic environments and may also influence the quality of drinking water. As knowledge is especially scarce about the fate of viruses when applied to fields in natural settings, this project sets out to investigate the leaching potential of six different microorganisms: E. coli and Enterococcus spp. (detected by colony assay), somatic coliphages (using plaque assays), and hepatitis E virus, porcine circovirus type 2, and group A rotavirus (by real-time polymerase chain reaction). All six microorganisms leached through the soil entering the tile drains situated at 1-m depth the first day following pig slurry application. The leaching pattern of group A rotavirus differed substantially from the pattern for somatic coliphages, which are otherwise used as indicators for virus contamination. Furthermore, group A rotavirus was detected in monitoring wells at 3.5-m depth up to 2 months after pig slurry application. The detection of viral genomic material in drainage water and shallow groundwater signifies a potential hazard to human health that needs to be investigated further, as water reservoirs used for recreational use and drinking water are potentially contaminated with zoonotic pathogens.  相似文献   

Helical magnetorotational instability of Taylor‐Couette flows in the Rayleigh limit and for quasi‐Kepler rotation     

G. Rüdiger  M. Schultz 《Astronomische Nachrichten》2008,329(7):659-666

The magnetorotational instability (MRI) of differential rotation under the simultaneous presence of axial and azimuthal components of the (current‐free) magnetic field is considered. For rotation with uniform specific angular momentum the MHD equations for axisymmetric perturbations are solved in a local short‐wave approximation. All the solutions are overstable for B_z · B_ϕ ≠ 0 with eigenfrequencies approaching the viscous frequency. For more flat rotation laws the results of the local approximation do not comply with the results of a global calculation of the MHD instability of Taylor‐Couette flows between rotating cylinders. – With B_ϕ and B_z of the same order the traveling‐mode solutions are also prefered for flat rotation laws such as the quasi‐Kepler rotation. For magnetic Prandtl number Pm → 0 they scale with the Reynolds number of rotation rather than with the magnetic Reynolds number (as for standard MRI) so that they can easily be realized in MHD laboratory experiments. – Regarding the nonaxisymmetric modes one finds a remarkable influence of the ratio B_ϕ/B_z only for the extrema. For B_ϕ ≫ B_z and for not too small Pm the nonaxisymmetric modes dominate the traveling axisymmetric modes. For standard MRI with B_z ≫ B_ϕ, however, the critical Reynolds numbers of the nonaxisymmetric modes exceed the values for the axisymmetric modes by many orders so that they are never prefered. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   

Acfer 217-A new member of the Rumuruti chondrite group (R)   总被引：1，自引：0，他引：1  

A. Bischoff  T. Geiger  H. Palme  B. Spettel  L. Schultz  P. Scherer  T. Loeken  P. Bland  R. N. Clayton  T. K. Mayeda  U. Herpers  B. Meltzow  R. Michel  B. Dittrich-Hannen 《Meteoritics & planetary science》1994,29(2):264-274

Abstract— Previously, three meteorites from Australia and Antarctica were described as a new chondritic “grouplet” (Carlisle Lakes, Allan Hills (ALH) 85151, Yamato (Y) ?75302; Rubin and Kallemeyn, 1989). This grouplet was classified as the “Carlisle Lakes-type” chondrites (Weisberg et al., 1991). Recently, one Saharan sample and four more Antarctic meteorites were identified to belong to this group (Acfer 217, Y-793575, Y-82002, PCA91002, PCA91241). The latter two are probably paired. With the meteorite Rumuruti, the first fall of this type of chondrite is known (Schulze et al., 1994). We report here on the Saharan meteorite Acfer 217 which has chemical and mineralogical properties very similar to Rumuruti and Carlisle Lakes. All eight members of this group, Rumuruti, Carlisle Lakes, ALH85151, Y-75302, Y-793575, Y-82002, Acfer 217, and the paired samples PCA91002 and PCA91241 justify the introduction of a new group of chondritic meteorites, the Rumuruti meteorites (R). Acfer 217 is a regolith breccia consisting of up to cm-sized clasts (～33 vol%) embedded in a fine-grained, well-lithified clastic matrix. The most abundant mineral is olivine (～72 vol%), which has a high Fa-content of 37–39 mol%. The major minerals (olivine, low-Ca pyroxene, Ca-pyroxene, and plagioclase) show some compositional variability indicating a slightly unequilibrated nature of the meteorite. Considering the mean olivine composition of Fa_{37.8 ± 5.7}, a classification of Acfer 217 as a R3.8 chondrite would result; however, Acfer 217 is a regolith breccia consisting of clasts of various petrologic types. Therefore, we suggest to classify Acfer 217 as a R3–5 chondrite regolith breccia. The bulk meteorite is very weakly shocked (S2). The bulk composition of Acfer 217 and other R-meteorites show that the R-meteorites are basically chondritic in composition. The pattern of moderately volatile elements is unique in R chondrites; Na and Mn are essentially undepleted, similar to ordinary chondrites, while Zn and Se contents are similar to concentrations in CM chondrites. The oxygen isotopic composition in Acfer 217 is similar to that of Rumuruti, Carlisle Lakes, ALH 85151, and Y-75302. In a δ¹⁷O vs. δ¹⁸O-diagram, the R-meteorites form a group well resolved from other chondrite groups. Acfer 217 was a meteoroid of common size with a radius between 15–65 cm and with a single stage exposure history. Based on ²¹Ne, an exposure age of about 35 Ma was calculated.  相似文献   

Noble gases in the St. Mesmin chondrite: Implications to the irradiation history of a brecciated meteorite     

Ludolf Schultz  Peter Signer 《Earth and Planetary Science Letters》1977,36(3):363-371

Helium, neon and argon were analysed in matrix samples and in different clasts of the polymict-brecciated LL-chondrite St. Mesmin. All clasts have high K-Ar ages with a mean value of4.40 ± 0.26Ga. One exotic H-group xenolith, however, has a K-Ar age of only1.36 ± 0.05Ga. The low age indicates that the St. Mesmin breccia was compacted to its present structure relatively late in its history and that the St. Mesmin meteorite developed from regolith material on the meteorite's parent body. This is further demonstrated by the high concentrations of solar noble gases in the matrix and the cosmic ray pre-exposure of one individual clast.  相似文献   

Zur Charakterisierung suspendierter Wasserinhaltsstoffe. Teil 2: Erste Ergebnisse der praktischen Anwendung der Analysenmethoden     

D. Schultz 《洁净——土壤、空气、水》1980,8(5):463-472

Nachdem in Teil 1 (Schultz ) die Bedeutung der Feststoffe für den Betrieb von Wasseraufbereitungsanlagen und Analysenmethoden zur Charakterisierung der Feststoffe diskutiert wurden, enthält Teil 2 die Ergebnisse von Untersuchungen an einem ausgewählten Vorfluter. Verschiedene Analysenmethoden werden getestet, miteinander verglichen und ihre Eignung zur Einschätzung des Leistungsverhaltens der Aufbereitungsanlagen überprüft.  相似文献   

Allan Hills 77081—an unusual stony meteorite     

L. Schultz  H. Palme  B. Spettel  H.W. Weber  H. Wänke  M. Christophe Michel-Levy  J.C. Lorin 《Earth and Planetary Science Letters》1982,61(1):23-31

Allan Hills (ALHA) 77081 is achondritic in texture while the mineral composition and the chemistry are chondritic with the exception of a few elements. An assignment to one specific group of ordinary chondrites is therefore difficult. In many respects this meteorite is similar to the unusual stone meteorite Acapulco. The REE pattern of ALHA 77081 is essentially flat and the distribution ratios of siderophile elements between metal and silicates are high compared to ordinary chondrites.Gas retention ages are 3.5±0.5 AE for U, Th-He and 4.50±0.15 AE for K-Ar. In spite of the high degree of recrystallisation the meteorite contains trapped noble gases in amounts comparable to type 4 chondrites.Cosmic ray tracks and spallogenic noble gases indicate a small preatmospheric radius of about 2–3 cm. Spallogenic nuclides produced by solar cosmic rays or stopped solar flare ions may be present.  相似文献   

Scaling the Microphysics Equations and Analyzing the Variability of Hydrometeor Production Rates in a Controlled Parameter Space     

Chungu Lu  Paul Schultz  Gerald L.Browning 《大气科学进展》2002,19(4):619-650

A set of microphysics equations is scaled based on the convective length and velocity scales.Comparisons are made among the dynamical transport and various microphysical processes.From the scaling analysis,it becomes apparent which parameterized microphysical processes present off-scaled influences in the integration of the set of microphysics equations. The variabilities of the parameterized microphysical processes are also studied using the approach of a controlled parameter space.Given macroscopic dynamic and thermodynamic conditions in different regions of convective storms,it is possible to analyze and compare vertical profiles of these processes.Bulk diabatic heating profiles for a cumulus convective updraft and downdraft are also derived from this analysis. From the two different angles,the scale analysis and the controlled-parameter space approach can both provide an insight into and an understanding of microphysics parameterizations.  相似文献