The paper considers four kinematic migration algorithms (procedures for converting the arrival times of reflected waves to the Earth’s surface into the depths of reflectors) using medium-velocity and ...reservoir velocity models of layered media: a standard algorithm for converting times to depths through average velocities; a modified medium-velocity algorithm that takes into account the slope of seismic boundaries; an algorithm for layer-by-layer recalculation of
t
0
lines to depths; and a variational kinematic migration algorithm based on ray tracing theory using an integrating a system of differential equations with specified initial conditions by the Runge–Kutta method. To study the possibilities and limitations of each algorithm, calculations were carried out using number of theoretical models of layered media that approximate real geological conditions. Based on the results of numerical experiments using the four kinematic migration algorithms considered in the paper, conclusions were drawn about the efficiency of using each of the algorithms to reconstruct the geological boundaries in models of media with varying complexity.
Full text
Available for:
EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
This paper presents a variational method for mathematical modeling of seismic wave kinematics developed by the Seismometry and Geoacoustics Chair at the Department of Geology, Moscow State ...University, for studying the kinematics of seismic waves of different types in 2D isotropic (gradient and layered) media. The problem of determining the paths of seismic rays was solved by integrating a system of differential equations with given initial conditions using the Runge–Kutta method. An algorithm to verify the accuracy and correctness of the solutions was studied and tested on a number of theoretical models of inhomogeneous media. The thus-developed ray tracing method was used to study the effect of the velocity gradient and of the geometry of seismic boundaries on the kinematics of reflected waves in multilayer media. Based on the results of mathematical modeling of the kinematics of reflected waves, conclusions were drawn about the limits of applicability of simplified models of horizontally layered media, which often approximate complex inhomogeneous media.
Full text
Available for:
EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
High-speed induction heating was used during strength tests in an oxidizing atmosphere of a composite material based on an aluminum-chromophosphate binder. Induction heating allows heating modes ...close to those of aircraft operating modes, which avoids the appearance of crystalline phases such as Al(PO3)3, Cr2O3, which arise under conditions of slow heating under classical methods of strength testing at elevated temperatures.
The results of the application of the variational ray tracing algorithm to studying the possibilities and limitations of one of the methods for solving the inverse kinematic problem of seismic ...exploration, namely, the method of homogeneous functions developed at the Department of Seismometry and Geoacoustics of Moscow State University are presented. As a result of the calculations carried out on synthetic models and field material, conclusions were drawn about the exploration possibilities and areas of application of the method of homogeneous functions. Model examples show that the method of homogeneous functions gives correct results only for simple media: vertically inhomogeneous or layered with slightly sloping boundaries, while folds or inclusions can be restored only at a qualitative level. When working with real field data, the method of homogeneous functions correctly restores the velocity structure of the section to a depth of one-third to one-half of the maximum depth of ray penetration. At the same time, only large anomalies with contrasting velocity values on the obtained velocity sections are to be identified and interpreted as real geological structures.
Full text
Available for:
EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Molecular genetic techniques (FISH and metagenomic analysis) were used to investigate prokaryotic complexes in native soils (gray forest soil and urbostratozema typical), soils contaminated by ...petroleum products (gasoline or diesel fuel), and soils subject to remediation by addition of a nitrogen-containing polysaccharide biopolymer chitin. The share of metabolically active prokaryotic cells in the hydrolytic complex of soil microcosms was determined, as well as their biomass and biodiversity. Compared to the control, in the pollutant-containing experimental microcosms, a decrease in the share of metabolically active prokaryotic cells was observed, as well as changes of the hydrolytic complex structure, such as an increase in the share of the phylum
Actinobacteria
(specifically of the genera
Galiella
and
Nocardioides
in the samples contaminated with gasoline and diesel fuel, respectively). Supplementing the hydrocarbon-contaminated system the biopolymer chitin resulted in processing of mixed-minerals with an increase in the number of layers of the smectite type and, as a result, in formation of aggregates and improved aeration. An increase in the number of metabolically active prokaryotic cells and decreased diversity of the soil prokaryotic complex were observed, which were probably associated with the development of a selective group of the hydrolytic complex of chitindegrading microorganisms.
Full text
Available for:
EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
The homogeneity (concentration boundary of the precipitation of the MgO phase) in sol-gelderived microcrystals with a mixed ZnO-MgO-FeO composition has been investigated using the optical and X-ray ...diffraction methods. It has been shown that optical spectroscopy in this case is a more sensitive method. The luminescence line of a deep center at 700 nm has been observed for the first time and used as an indication of the precipitation of the MgO phase. Based on the experimental data, the concentration boundary of the precipitation of the MgO phase is evaluated to be 4–10 at %, which is in good agreement with the available theoretical estimate.
Full text
Available for:
DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, SIK, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Persistent photoconductivity is observed in ZnO single crystals and ceramics together with persistence of electron paramagnetic resonance (EPR) spectra of defects and impurity centers. It is shown ...that when the light is switched on and off the microwave conductivity detected from absorption of the microwave field is well correlated with the dc-conductivity measured with electrical contacts applied to the sample. The microwave photoconductivity arises together with light-induced EPR spectra and persists after switching off the light. Coexistence of the conductivity and EPR spectra shows that the photoexcited electrons cannot return back to paramagnetic centers. The persistent photoconductivity in ZnO ceramics is large in comparison with the effect observed in powders prepared from the same material and in ZnO single crystals. This suggests that surface conductivity is the dominant mechanism of persistent photoconductivity in ZnO.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
YBCO films were prepared by pulsed laser deposition from nanocrystalline targets doped with different concentrations of BaZrO3 ranging from c = 0.9 to 9.0 wt%. The critical temperature of the films ...decreases almost linearly with increasing BaZrO3 content whereas the critical current density shows a maximum near 3.9 wt%. In comparison with undoped YBCO films the accommodation field B* is considerably enhanced and the critical current density is improved in high fields in the films doped with BaZrO3, e.g. for c = 3.9 wt% by factor of 4.5 in a field of 5 T at 5 K. In the doped films the BaZrO3 particles grow epiaxially with YBCO. Transmission electron microscopy results show that the density of the BaZrO3 particles increases with increasing doping but the particle size remains practically the same (5-10 nm).
The competitive environment orients rural producers to produce safe, high-quality products. The solution of this problem is impossible without the use of reliable and timely production information ...obtained by modern means of measurement. In the list of parameters of the system of operational decisionmaking in the production of grain and seeds, the determining role belongs to information about their moisture content. Reliable and timely information on humidity can significantly reduce the technical, technological and social risks affecting the economy of agricultural enterprises. Currently, the market of the necessary complex of grain moisture meters is occupied mainly by foreign developments. The most popular field electric moisture meters are not produced by domestic instrument-making companies. Foreign devices are graded on varieties of crops grown in completely different climatic and soil conditions. There are differences in the standard means and methods of grain preparation, which are used by manufacturers in the calibration of devices. In order to avoid risks when using imported devices, it is necessary to assess their adaptability to domestic crops and conditions of use. The article presents the results of a study of a new model from the line of capacitive moisture meters produced by the well-known Finnish company Farmcomp. The defining concept of the device model is the minimization of random errors caused by the user's actions, and automatic compensation of the influence of the volume density (nature) of the grain mass. The complexity of measurement technologies and the limited humidity range reduce the possibility of using the device in production conditions. The methods used in the device to compensate for factors affecting its readings do not fully provide the results expected from their use. Calibration of the device on domestic crops and varieties in the ranges of change of their basic properties (humidity, volume density), characteristic for the Russian conditions is necessary.
PDF
