Artificial screen for reducing seismic vibration generated by blasting     

Dragan Bogunovic  Vladislav Kecojevic 《Environmental Geology》2007,53(3):517-525

The purpose of blasting operations is rock fragmentation. Blasting is a key component in the overall rock fragmentation system - the first element of the ore extraction process. It provides appropriate rock material granulation or size that is suitable for loading and transportation. However, in spite of many advantages explosives have, their usage may cause environmental problem such as seismic vibration. One of the solutions to this particular problem may be application of an artificial screen as a barrier to the seismic wave path. The results of experimental research on the artificial screen concept, its characteristics and role in attenuation of seismic effects generated by blasting are presented. The experiment is based on two physical phenomena: (1) the size and degree of discontinuity and (2) the reflection and refraction of seismic waves. More than 1,500 laboratory measurements were conducted with different combinations of screen sizes, positions of the screen to blasting source, and intensities of blasting impulses. The results of the study show reduction of generated vibrations up to 58% by employment of artificial screens.  相似文献   

The protolith nature of diamondiferous metamorphic rocks of the Kokchetav Massif     

Vladislav Shatsky  Emil Jagoutz  Olga Kozmenko  Alexey Ragozin  Sergei Skuzovatov  Nikolai Sobolev 《《地质学报》英文版》2018,92(Z1):173-173

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Solar energetic particle events at the rise phase of the 23rd solar activity cycle registered aboard the spacecraft &;#x201C;INTERBALL-2&;#x201D;     

Vladislav Timofeev  Sergey Starodubtsev 《Journal of Astrophysics and Astronomy》2000,21(3-4):251-254

The experiment with 10K-80 aboard the INTER-BALL-2 (which detects protons with energies > 7, 27–41, 41–58, 58–88, 88–180 and 180–300 MeV) registered six events of the solar energetic particle (SEP) increase. These events are during the initial rise phase of the 23rd solar activity cycle. Solar flares with the SEP generation are accompanied by coronal mass ejection (CME). Here we analyze the dynamics of the differential energy spectrum at different phases of the SEP increase.  相似文献   

Temporary Array Data for Studying Seismic Anisotropy of Variscan Massifs – The Armorican Massif,French Massif Central And Bohemian Massif     

Plomerová  Jaroslava  Granet  Michel  Judenherc  Sebasten  Achauer  Ulrich  Babuška  Vladislav  Jedlička  Petr  Kouba  Daniel  Vecsey  Luděk 《Studia Geophysica et Geodaetica》2000,44(2):195-209

We present the first results of a comparison of deep lithosphere structure of three Variscan massifs - the Armorican Massif, French Massif Central and Bohemian Massif, as revealed by recent tomographic studies of seismic anisotropy. The data originate from several field measurements made in temporary arrays of stations equipped with both short-period and broadband seismometers with digital recording. The study is based on teleseismic body waves and a joint inversion of anisotropic data (P-residual spheres, the fast shear-wave polarizations and split times) and demonstrates that the three Variscan massifs appear to consist of at least two parts with different orientation of large-scale fabric derived from seismic anisotropy. The boundaries of anisotropic lithospheric domains are related to prominent tectonic features recognised on the surface as sutures, shear zones or transfer fault zones, as well as grabens, thus indicating that some of them extend deep through the entire lithosphere.  相似文献   

The eccentric Kozai–Lidov effect as a resonance phenomenon     

Vladislav V. Sidorenko 《Celestial Mechanics and Dynamical Astronomy》2018,130(1):4

Exploring weakly perturbed Keplerian motion within the restricted three-body problem, Lidov (Planet Space Sci 9:719–759, 1962) and, independently, Kozai (Astron J 67:591–598, 1962) discovered coupled oscillations of eccentricity and inclination (the KL cycles). Their classical studies were based on an integrable model of the secular evolution, obtained by double averaging of the disturbing function approximated with its first non-trivial term. This was the quadrupole term in the series expansion with respect to the ratio of the semimajor axis of the disturbed body to that of the disturbing body. If the next (octupole) term is kept in the expression for the disturbing function, long-term modulation of the KL cycles can be established (Ford et al. in Astrophys J 535:385–401, 2000; Naoz et al. in Nature 473:187–189, 2011; Katz et al. in Phys Rev Lett 107:181101, 2011). Specifically, flips between the prograde and retrograde orbits become possible. Since such flips are observed only when the perturber has a nonzero eccentricity, the term “eccentric Kozai–Lidov effect” (or EKL effect) was proposed by Lithwick and Naoz (Astrophys J 742:94, 2011) to specify such behavior. We demonstrate that the EKL effect can be interpreted as a resonance phenomenon. To this end, we write down the equations of motion in terms of “action-angle” variables emerging in the integrable Kozai–Lidov model. It turns out that for some initial values the resonance is degenerate and the usual “pendulum” approximation is insufficient to describe the evolution of the resonance phase. Analysis of the related bifurcations allows us to estimate the typical time between the successive flips for different parts of the phase space.  相似文献   

Spectral harmonic analysis and synthesis of Earth’s crust gravity field   总被引：5，自引：0，他引：5  

Robert Tenzer  Pavel Novák  Peter Vajda  Vladislav Gladkikh  Hamayun 《Computational Geosciences》2012,16(1):193-207

We developed and applied a novel numerical scheme for a gravimetric forward modelling of the Earth’s crustal density structures based entirely on methods for a spherical analysis and synthesis of the gravitational field. This numerical scheme utilises expressions for the gravitational potentials and their radial derivatives generated by the homogeneous or laterally varying mass density layers with a variable height/depth and thickness given in terms of spherical harmonics. We used these expressions to compute globally the complete crust-corrected Earth’s gravity field and its contribution generated by the Earth’s crust. The gravimetric forward modelling of large known mass density structures within the Earth’s crust is realised by using global models of the Earth’s gravity field (EGM2008), topography/bathymetry (DTM2006.0), continental ice-thickness (ICE-5G), and crustal density structures (CRUST2.0). The crust-corrected gravity field is obtained after modelling and subtracting the gravitational contribution of the Earth’s crust from the EGM2008 gravity data. These refined gravity data mainly comprise information on the Moho interface and mantle lithosphere. Numerical results also reveal that the gravitational contribution of the Earth’s crust varies globally from 1,843 to 12,010 mGal. This gravitational signal is strongly correlated with the crustal thickness with its maxima in mountainous regions (Himalayas, Tibetan Plateau and Andes) with the presence of large isostatic compensation. The corresponding minima over the open oceans are due to the thin and heavier oceanic crust.  相似文献   

Dissipative structures in a nonlinear dynamo     

Andrew D. Gilbert  Yannick Ponty  Vladislav Zheligovsky 《地球物理与天体物理流体动力学》2013,107(6):629-653

This article considers magnetic field generation by a fluid flow in a system referred to as the Archontis dynamo: a steady nonlinear MHD state is driven by a prescribed body force. The field and flow become almost equal and dissipation is concentrated in cigar-like structures centred on straight-line separatrices. Numerical scaling laws for energy and dissipation are given that extend previous calculations to smaller diffusivities. The symmetries of the dynamo are set out, together with their implications for the structure of field and flow along the separatrices. The scaling of the cigar-like dissipative regions, as the square root of the diffusivities, is explained by approximations near the separatrices. Rigorous results on the existence and smoothness of solutions to the steady, forced MHD equations are given.  相似文献   

Effect of small potassium-rich dykes on regional gamma-spectrometry image of a potassium-poor volcanic complex: A case from the Doupovské hory Volcanic Complex, NW Czech Republic   总被引：1，自引：0，他引：1  

Skcelov Zuzana  Rapprich Vladislav  Ml och Bed&#x;ich 《Journal of Volcanology and Geothermal Research》2009,187(1-2):26-32

Basaltic rocks with low K, U and Th contents dominate the entire Volcanic Complex of the Doupovské hory Mts. Significant potassium anomaly exceeding 1.5 atomic wt.% of potassium over an area of 4 × 8 km and 2 atomic wt.% of potassium over an area of 2 × 6 km was defined by airborne gamma-ray spectrometry above the central part of the Doupovské hory Volcanic Complex. The following detailed field study, supported by field and laboratory gamma-spectrometry measurements and geochemical analyses of rock samples, resulted in discovery of a swarm of potassium-rich trachytic dykes. The existence of such highly-differentiated rocks in the volcanic complex was unknown till present. These dykes are commonly less than 1 m wide, but their potassium content varies between 4 and 8 atomic wt.%. Owing to this high-K composition and relative abundance of dykes, the dyke rocks significantly modify the regional pattern of gamma-spectrometry data. The potassium anomaly cannot be explained by the presence of Flurbühl intrusive body dominated by ijolites and essexites, as all these rocks are poor in K, with potassium typically not exceeding 1.5 wt.%. On the other hand, much more extensive intermediate trachybasaltic lavas with K content varying within the range 1.8–3 wt.% cause only minor or undetectable anomalies.  相似文献   

Seismic anisotropy of the mantle lithosphere beneath the Swedish National Seismological Network (SNSN)     

Tuna Eken  Jaroslava Plomerová  Roland Roberts  Ludek Vecsey  Vladislav Babuška  Hossein Shomali  Reynir Bodvarsson 《Tectonophysics》2010,480(1-4):241-258

Body-wave analysis — shear-wave splitting and P travel time residuals — detect anisotropic structure of the upper mantle beneath the Swedish part of Fennoscandia. Geographic variations of both the splitting measurements and the P-residual spheres map regions of different fabrics of the mantle lithosphere. The fabric of individual mantle domains is internally consistent, usually with sudden changes at their boundaries. Distinct backazimuth dependence of SKS splitting excludes single-layer anisotropy models with horizontal symmetry axes for the whole region. Based upon joint inversion of body-wave anisotropic parameters, we instead propose 3D self-consistent anisotropic models of well-defined mantle lithosphere domains with differently oriented fabrics approximated by hexagonal aggregates with plunging symmetry axes. The domain-like structure of the Precambrian mantle lithosphere, most probably retaining fossil fabric since the domains' origin, supports the idea of the existence of an early form of plate tectonics during the formation of continental cratons already in the Archean. Similarly to different geochemical and geological constraints, the 3D anisotropy modelling and mapping of fabrics of the lithosphere domains contribute to tracking plate tectonics regimes back in time.  相似文献   

Saxothuringian-Moldanubian Suture and Predisposition of Seismicity In The Western Bohemian Massif     

Babuška  Vladislav  Plomerová  Jaroslava 《Studia Geophysica et Geodaetica》2000,44(2):292-306

We modelled the thickness and seismic anisotropy of the subcrustal lithosphere from the variations of P-wave delay times and the shear-wave splitting observed at seismological observatories and portable stations in the western part of the Bohemian Massif. The Saxothuringian lithosphere is characterized by a total thickness between 90 and 120 km, the Moldanubian lithosphere is generally thicker –120-140 km, on the average. The subcrustal lithosphere of both units is characterised by divergently dipping anisotropic structures and the suture between them is marked by a lithosphere thinning to about 80km. Within the subcrustal lithosphere a complex structure of the transition of both units extends to about 150 km toward the south. We suggest that the Saxothuringian-Moldanubian suture has created a zone of mechanical predisposition for the Tertiary Ohe (Eger) Graben, as well as for the occurrence of earthquake swarms in the region. Most earthquakes occur within the brittle part of the upper crust above the crossing of the suture between the Saxothuringian in the north and the Moldanubian and the Tepl´-Barrandian in the south, with the tectonically active Mariánské Lázn fault.  相似文献