Surface Miners: Evaluation of the Production Rate and Cutting Performance Based on Rock Properties and Specific Energy     

Chiara Origliasso  Marilena Cardu  Vladislav Kecojevic 《Rock Mechanics and Rock Engineering》2014,47(2):757-770

The purpose of this research was to evaluate the production rate (PR) and cutting performance of surface miners (SM) based on rock properties and specific energy (SE). We use data from equipment manufacturers and experimental data in this study and propose a new method and equations to determine both the PR and the cutting speed of SM. The unconfined compressive strength (UCS) of the rock, its abrasivity, and the machine’s engine power are the three most important factors influencing the PR. Moreover, the cutting depth, UCS, and engine power have a significant impact on the cutting speed. We propose a new method and equations to determine the energy required to cut a volume unit and a surface unit, i.e., specific energy, and establish the relationship between SE, UCS, and PR. The results of this study can be used by surface miner operators to evaluate the applicability of the machines to a specific mine site.  相似文献   

The third ural regional lithological meeting     

P. P. Timofeev  V. P. Alekseev  L. V. Anfimov 《Lithology and Mineral Resources》2000,35(1):86-86

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Ground-based measurements of total ozone content by the infrared method     

Ya. A. Virolainen  Yu. M. Timofeev  D. V. Ionov  A. V. Poberovskii  A. M. Shalamyanskii 《Izvestiya Atmospheric and Oceanic Physics》2011,47(4):480-490

To interpret the ground-based measurements of the spectra of direct solar infrared radiation with the help of a Brucker Fourier-spectrometer, a technique for determining the total ozone content (TOC) was developed and implemented. The TOC was determined using six spectral intervals of an ozone-absorption band of 9.6 μm and the shortwave panel of a carbon-dioxide-absorption band of 15 μm, where the impact of other atmospheric parameters on the measured solar radiation was reduced to a minimum. The potential errors of the infrared method for determining the TOC for the chosen spectral scheme with the influence of measurement errors and vertical profiles of temperature are less than 1% for different signal-to-noise ratios and zenith angles of the sun. We analyzed 269 high-resolution (0.005–0.008 cm^?1) spectra of solar infrared radiation measured in Peterhof over 52 days from March to November, 2009. The resulting values of TOC were compared with the results of independent ground-based TOC measurements in Voeikovo (Main Geophysical Observatory) using a Dobson spectrophotometer and an M-124 ozonometer, as well as with the Ozone Monitoring Instrument (OMI) satellite data. The mean errors between the results of TOC measurements with the help of the three ground-based probes constitute no more than 0.4%. The rms errors between data obtained by the Brucker spectrometer and the given satellite and ground-based probes constitute 3–4%. A comparison between different series of measurements indicated that the upper estimate for the error of TOC measurements by the Brucker spectrometer was 2.5–3% (when the possible spatial and temporal errors in measurements are disregarded). An analysis of the diurnal variations in the TOC measurements for stable atmospheric conditions yields an upper estimate of ～3 DU (around 1%) for the random component of error in TOC measurements by the Brucker spectrometer.  相似文献   

Dissipation of baroclinic tidal energy and diapycnal mixing in the White Sea     

B. A. Kagan  A. A. Timofeev 《Izvestiya Atmospheric and Oceanic Physics》2011,47(5):642-648

The modeling results obtained using the original version of the three-dimensional finite-element hydrostatic model QUODDY-4 testify that the spatial distributions of dissipation of baroclinic tidal energy and the related coefficient of diapycnal mixing in the deepwater stratified subdomain of the White Sea (the Basin and Kandalaksha and Dvina bays together) are highly similar to those found for low- and midlatitude oceans. It is in the open part of the sea that their values remain equal to the minimum possible values determined by the molecular kinematic viscosity; at its lateral boundaries (not all boundaries, but only individual segments (sites of mixing)), their values increase. In the shallow homogeneous subdomain of the White Sea, the dissipation of baroclinic tidal energy is considerably larger than in the deep stratified subdomain. Accordingly, the vertical eddy viscosity in the first subdomain is a few orders of magnitude higher than the coefficient of diapycnal mixing in the second subdomain. This is caused by an increased tidal velocity due to reduced depths.  相似文献   

Manifestation of the 399-day variations in solar wind parameters     

Skryabin  N. G.  Timofeev  V. E.  Miroshnichenko  L. I.  Samsonov  S. N. 《Astronomy Letters》2005,31(12):832-835

Astronomy Letters - Based on a large series (N = 14 038) of daily solar wind densities, we obtained the fluctuation power spectrum. The spectrum shows that the 399-day variation (the synodic period...  相似文献   

Considering temperature dependence of thermo-physical properties of sandy soils in two scenarios of oil pollution     

Aleksey V. Malyshev  Anatoly M. Timofeev 《寒旱区科学》2014,6(4):0302-0308

We analyzed the heat conductivity and volumetric heat capacity of sandy soil contaminated in two scenarios of oil pollution, and also determined the temperature dependencies of these changed thermophysical properties. In the first pollution scenario, the oil product was introduced into wet river sand, and in the second case, dry sand was contaminated by the oil product and was then moistened with water. By considering these two scenarios as multicomponent dispersion systems with varying degrees of contamination and humidity, and by using a polystructural granular model with pore spaces and closed inclusions, we calculated that the heat conductivity of the sandy soil increased under the first pollution scenario and decreased under the second, but the change in the volumetric heat capacity of the sandy soil was proportional only to the amount of oil pollution, not the manner in which it was introduced. We also determined the temperature dependencies of these two thermophysical properties of sandy soil when polluted by oil, of which information will be useful for future containment and remediation of oil-contaminated soil.  相似文献   

Distribution of thallium and accompanying metals in tree rings of Scots pine (Pinus sylvestris L.) from a smelter-affected area     

Aleš Vaněk  Vladislav Chrastný  Leslaw Teper  Jerzy Cabala  Vít Penížek  Michael Komárek 《Journal of Geochemical Exploration》2011

Distribution of Tl, Zn, Cd, Pb, K, Ca, Mg and Mn and Pb isotopic composition in tree rings of Scots pine (Pinus sylvestris L.) from an area affected by primary Zn smelting (Olkusz, southern Poland) were investigated. Elevated concentrations of Tl (up to 0.8 mg kg⁻¹) in pine trees imply that conifers tend to accumulate this metal to some extent. A generally positive relationship between soil and tree-ring Tl levels was identified. The Tl patterns in stem wood did not correspond to changes in Tl deposition; the lateral translocation of Tl in the sapwood and its accumulation at the sapwood-heartwood boundary (i.e., in the inner sapwood) is suggested. It is probable that the specific behavior of Tl in trees results from its biogeochemical analogy with K. In contrast, tree-ring patterns of Zn and Cd significantly correlated with their deposition; nevertheless, a partial shift of these metals towards the stem center cannot be excluded. The isotopic composition of Pb (²⁰⁶Pb/²⁰⁷Pb ~ 1.172–1.184) in trees and underlying soils revealed the predominant influence of smelter emissions (²⁰⁶Pb/²⁰⁷Pb ~ 1.17) on Pb contamination. Analysis of main nutrients (Ca, Mg and Mn) in wood reflected environmental changes related to acid deposition.  相似文献   

Mean-field equations for weakly nonlinear two-scale perturbations of forced hydromagnetic convection in a rotating layer     

Vladislav Zheligovsky 《地球物理与天体物理流体动力学》2013,107(5):489-540

We consider stability of regimes of hydromagnetic thermal convection in a rotating horizontal layer with free electrically-conducting boundaries, to perturbations involving large spatial and temporal scales. Equations governing the evolution of weakly nonlinear mean perturbations are derived under the assumption that the α-effect is insignificant in the leading-order (e.g. due to a symmetry of the system). The mean-field equations generalise the standard equations of hydromagnetic convection: New terms emerge – a second-order linear operator representing the combined eddy diffusivity and quadratic terms associated with the eddy advection. If the perturbed CHM regime is nonsteady and insignificance of the α-effect in the system does not rely on the presence of a spatial symmetry, the combined eddy diffusivity operator also involves a nonlocal pseudodifferential operator. If the perturbed CHM state is almost symmetric, α-effect terms appear in the mean-field equations as well. Near a point of a symmetry-breaking bifurcation, cubic nonlinearity emerges in the equations. All the new terms are in general anisotropic. A method for evaluation of their coefficients is presented; it requires solution of a significantly smaller number of auxiliary problems than in a straightforward approach.  相似文献   

Changes in the dynamics/energetics of surface and internal tides in the White Sea on the coexistence of shore-fast and drifting ice covers     

B.A. Kagan  A.A. Timofeev 《Continental Shelf Research》2010

The results of modeling for _M2${\mathrm{M}}_2$ surface and internal tides in the White Sea are discussed. These results are obtained for the case when shore-fast and drifting ice covers are present concurrently. It is assumed that the interface between ice covers is of non-tidal origin (i.e., it is pre-assigned) and that ice rheology is viscous-elastic, representative of the low temperatures typical of winter conditions. Emphasis is placed on tidal energetics and, in particular, on the averaged (over a tidal cycle) values of the density and the dissipation rate of barotropic/baroclinic tidal energy. It is shown that in the White Sea, unlike in other marginal seas, the averaged (over a tidal cycle) and depth-integrated density of baroclinic tidal energy for the combined ice cover is much less than the same defined density of barotropic tidal energy. Similarly, the averaged and integrated (over the volume of the White Sea) rate of baroclinic tidal energy dissipation is much less than the same defined rate of barotropic tidal energy dissipation. The latter, in turn, is greater than for the shore-fast ice cover, but is smaller than for the drifting ice cover.  相似文献   

Three-dimensional velocity model of the crust of the Bohemian Massif and its effects on seismic tomography of the upper mantle     

Hana Karousová  Jaroslava Plomerová  Vladislav Babu?ka 《Studia Geophysica et Geodaetica》2012,56(1):249-267

We have compiled a representative three-dimensional P-velocity model of the crust of the Bohemian Massif (BM) to provide a basis for removing effects of the crustal structure in teleseismic tomography of the upper mantle. The model is primarily based on recently published 2D velocity models from findings of wide-angle refraction and near-vertical reflection seismic profiles of CELEBRATION 2000, ALP 2002, and SUDETES 2003 experiments. The best fitting 3D model of the BM crust (NearNeighbour model) is complemented by velocities according to the reference Earth model at sites where data are sparse, which precludes creating artificial heterogeneities that are products of interpolation method. To test the model, we have performed tomographic inversions of the P-wave travel times measured during the BOHEMA II experiment and compared the results obtained with and without crustal corrections. The tests showed that the presented crustal model decreases magnitudes of velocity perturbations leaking from the crust to the mantle in the western part of the BM. The tomographic images also indicated a highvelocity anomaly in the lower crust or just beneath the crust in the Brunovistullian unit. Such anomaly is not described by our model of the crust since no seismic profile intersects this part of the unit. The tests also indicated that crustal corrections are of the great importance especially for interpretations of the uppermost mantle down to depths of about 100 km.  相似文献