Cluster mass functions in the quintessential universe     

Ewa L. &#;okas  Paul Bode  Yehuda Hoffman 《Monthly notices of the Royal Astronomical Society》2004,349(2):595-602

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Constructing merger trees that mimic N-body simulations     

Eyal Neistein  Avishai Dekel 《Monthly notices of the Royal Astronomical Society》2008,383(2):615-626

We present a simple and efficient empirical algorithm for constructing dark matter halo merger trees that reproduce the distribution of trees in the Millennium cosmological N -body simulation. The generated trees are significantly better than EPS trees. The algorithm is Markovian, and it therefore fails to reproduce the non-Markov features of trees across short time-steps, except for an accurate fit to the evolution of the average main progenitor. However, it properly recovers the full main-progenitor distribution and the joint distributions of all the progenitors over long-enough time-steps,  Δω≃Δ z > 0.5  , where  ω≃ 1.69/ D ( t )  is the self-similar time variable and D ( t ) refers to the linear growth of density fluctuations. We find that the main-progenitor distribution is lognormal in the variable  σ²( M )  , the variance of linear density fluctuations in a sphere encompassing mass M . The secondary progenitors are successfully drawn one by one from the remaining mass using a similar distribution function. These empirical findings may be clues to the underlying physics of merger-tree statistics. As a byproduct, we provide useful, accurate analytic time-invariant approximations for the main-progenitor accretion history and for halo merger rates.  相似文献   

Properties and Processes of Crustal Fault Zones: Volume II     

Yehuda Ben-Zion  Antonio Rovelli 《Pure and Applied Geophysics》2015,172(5):1003-1005

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A Continuum Damage–Breakage Faulting Model and Solid-Granular Transitions     

Vladimir Lyakhovsky  Yehuda Ben-Zion 《Pure and Applied Geophysics》2014,171(11):3099-3123

We present a thermodynamically-based formulation for mechanical modeling of faulting processes in the seismogenic brittle crust using a continuum damage–breakage rheology. The model combines previous results of a continuum damage framework for brittle solids with continuum breakage mechanics for granular flow. The formulation accounts for the density of distributed cracking and other internal flaws in damaged rocks with a scalar damage parameter, and addresses the grain size distribution of a granular phase in a failure slip zone with a breakage parameter. The stress–strain relation and kinetics of the damage and breakage processes are governed by the total energy function of the system, which combines the energy of the damaged solid with the energy of the granular material. A dynamic brittle instability is associated with a critical level of damage in the solid, leading to loss of convexity of the solid energy function and transition to a granular phase associated with lower energy level. A non-local formulation provides an intrinsic length scale associated with the internal damage structure, which leads to a finite length scale for damage localization that eliminates the unrealistic singular localization of local models. Shear heating during deformation can lead to a secondary finite-width internal localization. The formulation provides a framework for studying multiple aspects of brittle deformation, including potential feedback between evolving elastic moduli and properties of the slip localization zone and subsequent rupture behavior. The model has a more general transition from slow deformation to dynamic rupture than that associated with frictional sliding on a single pre-existing failure zone, and gives time and length scales for the onset of the dynamic fracturing process. Several features including the existence of finite localization width and transition from slow to rapid dynamic slip are illustrated using numerical simulations. A configuration having an existing narrow slip zone with localized damage produces for appropriate loading conditions an overall cyclic stick–slip motion. The simulated frictional response includes transitions from friction coefficient of ~0.7 at low slip velocity to dynamic friction below 0.4 at slip rates above ~0.1 m/s, followed by rapidly increasing friction for slip rates above ~1 m/s, consistent with laboratory observations.  相似文献   

Properties and Processes of Crustal Fault Zones: Volume I     

Yehuda Ben-Zion  Antonio Rovelli 《Pure and Applied Geophysics》2014,171(11):2863-2865

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Evolution and degradation of flat‐top mesas in the hyper‐arid Negev,Israel revealed from 10Be cosmogenic nuclides          下载免费PDF全文

Ronen Boroda  Ari Matmon  Rivka Amit  Itai Haviv  Maurice Arnold  Georges Aumaître  Didier L. Bourlès  Karim Keddadouche  Yehuda Eyal  Yehouda Enzel 《地球表面变化过程与地形》2014,39(12):1611-1621

Mesas are ubiquitous landforms in arid and semiarid regions and are often characterized by horizontal stratified erodible rocks capped by more resistant strata. The accepted conceptual model for mesa evolution and degradation considers reduction in the width of the mesa flat‐top plateau due to cliff retreat but ignores possible denudation of the mesa flat‐top and the rates and mechanism of erosion. In this study we examine mesas in the northeastern hyperarid Negev Desert where they appear in various sizes and morphologies and represent different stages of mesa evolution. The variety of mesas within a single climatic zone allows examination of the process of mesa evolution through time. Two of the four sites examined are characterized by a relatively wide (200–230 m) flat‐top and a thick caprock whereas the other two are characterized by a much narrower remnant flat‐top (several meters) and thinner caprock. We use the concentration of the cosmogenic nuclide ¹⁰Be for: (a) determining the chronology of the various geomorphic features associated with the mesa; and (b) understanding geomorphic processes forming the mesa. The ¹⁰Be data, combined with field observations, suggest a correlation between the width of flat‐top mesa and the denudation and cliff retreat rates. Our results demonstrate that: (a) cliff retreat rates decrease with decreasing width of the flat‐top mesa; (b) vertical denudation rates increase with decreasing width of the flat‐top mesa below a critical value (~60 m, for the Negev Desert); (c) the reduction in the width of the flat‐top mesa is driven mainly by cliff retreat accompanied by extremely slow vertical denudation rate which can persist for a very long time (>10⁶ Ma); and (d) when the width of the mesa decreases below a certain threshold, its rate of denudation increases dramatically and mesa degradation is completed in a short time. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

On the equivalence of areal and volumetric averages in transport phenomena in porous media     

Jacob Bear  Yehuda Bachmat 《Advances in water resources》1983,6(1):59-62

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Potency-magnitude scaling relations for southern California earthquakes with 1.0 < M_L < 7.0     

Yehuda Ben-Zion  Lupei Zhu 《Geophysical Journal International》2002,148(3):F1-F5

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Three-dimensional calculations of fault-zone-guided waves in various irregular structures   总被引：2，自引：0，他引：2  

Gunnar Jahnke  Heiner Igel  Yehuda Ben-Zion 《Geophysical Journal International》2002,151(2):416-426

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New perspectives on the Negev continental bridge     

Yehuda Gradus  Eliahu Stern 《Geoforum》1977,8(5-6)

In a paper written immediately after the reopening of the Suez Canal in 1975, a question was raised: is the Israeli Negev a viable alternative to the Suez Canal? (Geoforum, 8, 29–32, 1977). The answer posted then was pessimistic — the continental land bridge was seen as having failed to function as a real alternative.Now, two years after the reopening of the Canal, it appears that the land bridge seems to be a more economically viable venture than previously suggested. The amount of cargo in transit over the land bridge and its percentage of the total port of Eilat traffic is increasing despite competition from the Canal. This phenomenon and new perspectives on the Negev land bridge are discussed in this follow-up paper.  相似文献