Brittle Deformation of Solid and Granular Materials with Applications to Mechanics of Earthquakes and Faults     

Yehuda Ben-Zion  Charles Sammis 《Pure and Applied Geophysics》2011,168(12):2147-2149

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Atmospheric mass deposition by captured planetesimals     

Eyal Iaroslavitz 《Icarus》2007,187(2):600-610

We examine the deposition of heavy elements in the envelope of a protoplanet growing according to the core accretion scenario of Pollack et al. [Pollack, J.B., Hubickyj, O., Bodenheimer, P., Lissauer, J.J., Podolak, M., Greenzweig, Y., 1996. Icarus 124, 62-85]. We use their atmospheric models and the deposition rates that they computed, and we calculate the amount of heavy elements that can be dissolved in the envelope. For planetesimals composed of a mixture of water, CHON, and rock, we find that almost all of the water is dissolved in the atmosphere. A substantial amount of CHON is also dissolved but it remains sequestered at high temperatures near the core. Some fraction of the rock is also dissolved in the very high temperature region near the core envelope boundary. If this dissolved material can be mixed upward later in the planet's evolution, the resulting structure would be much closer to that determined by matching the moments of Jupiter's gravitational field.  相似文献   

Natural downsizing in hierarchical galaxy formation     

Eyal Neistein  Frank C. van den Bosch  Avishai Dekel 《Monthly notices of the Royal Astronomical Society》2006,372(2):933-948

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The distribution function of dark matter in massive haloes     

Rados&#;aw Wojtak  Ewa L. &#;okas  Gary A. Mamon  Stefan Gottlöber  Anatoly Klypin  Yehuda Hoffman 《Monthly notices of the Royal Astronomical Society》2008,388(2):815-828

We study the distribution function (DF) of dark matter particles in haloes of mass range  10¹⁴–10¹⁵ M_⊙  . In the numerical part of this work we measure the DF for a sample of relaxed haloes formed in the simulation of a standard Λ cold dark matter (ΛCDM) model. The DF is expressed as a function of energy E and the absolute value of the angular momentum L , a form suitable for comparison with theoretical models. By proper scaling we obtain the results that do not depend on the virial mass of the haloes. We demonstrate that the DF can be separated into energy and angular momentum components and propose a phenomenological model of the DF in the form     . This formulation involves three parameters describing the anisotropy profile in terms of its asymptotic values (β₀ and  β_∞  ) and the scale of transition between them ( L ₀). The energy part   f _E ( E )  is obtained via inversion of the integral for spatial density. We provide a straightforward numerical scheme for this procedure as well as a simple analytical approximation for a typical halo formed in the simulation. The DF model is extensively compared with the simulations: using the model parameters obtained from fitting the anisotropy profile, we recover the DF from the simulation as well as the profiles of the dispersion and kurtosis of radial and tangential velocities. Finally, we show that our DF model reproduces the power-law behaviour of phase-space density   Q =ρ( r )/σ³( r )  .  相似文献   

Statistical Seismology     

David Vere-Jones  Yehuda Ben-Zion  Ramón Zúñiga 《Pure and Applied Geophysics》2005,162(6-7):1023-1026

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Stochastic Branching Models of Fault Surfaces and Estimated Fractal Dimensions     

Eric Libicki  Yehuda Ben-Zion 《Pure and Applied Geophysics》2005,162(6-7):1077-1111

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Standing-water deposits as indicators of Late Quaternary dune migration in the northwestern Negev,Israel     

Mordeckai Magaritz  Yehuda Enzel 《Climatic change》1990,16(3):307-318

Late Quaternary playa (stand-water) deposits are present in river channels upstream from dune fields in the northwestern Negev and represent a drainage disordering caused by dune migration during periods of aridity. These deposits are associated with modifications in the drainage system, including course changes and piracy, caused by dunes blocking drainage networks. Radiocarbon dates from the standing-water sediments indicate the occurrence of two periods of aridity: (1) 20,900 to 16,000 years B.P. and (2) 11,680 to 10,300 years B.P. These two periods indicate a correlation between glacial advances in Europe and dry intervals in the Near East during the Upper Pleistocene. We suggest that spatial and temporal associations between standing-water deposits, modifications in stream direction, soil formation and the dunes themselves can serve as a good indicator for the timing of dune migration.  相似文献   

Simulation of SH- and P-SV-wave propagation in fault zones   总被引：3，自引：0，他引：3  

Heiner Igel  Yehuda Ben-Zion  Peter C. Leary 《Geophysical Journal International》1997,128(3):533-546

Seismic fault-zone (FZ) trapped waves provide a potentially high-resolution means for investigating FZ and earthquake properties. Seismic waves emitted within and travelling along low-velocity FZ layers may propagate many kilometres within the low-velocity structure associated with the fault. Waveform observation of FZ trapped waves can be modelled in terms of FZ layer velocities, thicknesses and attenuation coefficients. This can greatly improve the resolution of imaged FZ structure and microearthquake locations. At present, broad-band theoretical seismograms are restricted to plane-parallel layers of uniform properties. However, it is not clear how realistic these models are compared with actual fault structures which could, for example, flare outwards near the surface, have irregular boundaries, interior heterogeneities, etc. To address these interpretational uncertainties, we perform finite-difference simulations for irregular FZ geometries and non-uniform material properties within the layers. The accuracy of the numerical solutions are verified by comparison with the analytical solution of Ben-Zion & Aki (1990) for plane-parallel structures. Our main findings are: (1) FZs can widen at the ctustal surface only slightly modifying the trapped waves; (2) velocity variations with depth destroy trapped wave propagation at all wavelengths; (3) FZ trapped waves can be obscured by the presence of a low-velocity surface layer; (4) models with short-scale random structures suggest that trapped waves average out irregular FZ geometries, and hence can be effectively modelled by average-property plane-layered media for the observed range of wavelengths.  相似文献   

A shallow fault-zone structure illuminated by trapped waves in the Karadere–Duzce branch of the North Anatolian Fault, western Turkey     

Yehuda Ben-Zion  Zhigang Peng  David Okaya  Leonardo Seeber  John G. Armbruster  Naside Ozer  rew J. Michael  Serif Baris  Mustafa Aktar 《Geophysical Journal International》2003,152(3):699-717

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The shape of the LoTr 5 planetary nebula     

Noah Brosch  Yehuda Hoffman † 《Monthly notices of the Royal Astronomical Society》1999,305(2):241-245

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