欧亚北部跨大陆交通经济带发展工程（英文）     

Peter BAKLANOV  Matvey ROMANOV  Vladimir KARAKIN  Alexey LANKIN 《资源与生态学报(英文版)》2015,6(2):110-113

跨西伯利亚大铁路的主要作用在于实现欧亚两洲西部和东部的交流。沿西伯利亚大铁路及其分支的交通经济带的形成意义重大。本文揭示了西伯利亚大铁路及其分支以及"一体化的欧亚基础设施系统"这一宏伟工程长远发展的主要特征,描述了西伯利亚大铁路和中国新丝绸之路影响区域的比较特征,提出了欧亚跨大陆板块交通经济带发展中面临的环境问题。研究认为,尽管在欧亚交通领域西伯利亚大铁路会面临一些竞争,但通过促进沿交通走廊区域的可持续发展,新丝绸之路建设将会为参与的国家带来显著的社会经济效益和环境效益,也必然会促进欧亚更密切的区域经济一体化和区域安全。  相似文献   

CAD Tool Simulates and Evaluates GPS Receiver Designs     

Michael Vorobiev  Alexey Zhdanov  Mark Zhodzishsky  Javad Ashjaee 《GPS Solutions》2000,4(1):13-20

A new computer-aided design (CAD) program called Falcon 3.0 has been created to simulate and evaluate receiver designs. This CAD tool aims to solve tasks at the design stage of navigation receivers that operate with signals from Navigational Satellite Time and Ranging (NAVSTAR) and Global Navigational Satellite System (GLONASS). Specific tasks include: · Defining the receiver frequency plan (frequencies of oscillators and filters that guarantee accuracy of the receiver) · Specifying parameters for the digital processing of received signal · Computing interpath and interchannel biases · Computing statistical characteristics of correlation signals I, Q, dl, and dQ · Calculating noise and multipath errors of measurements · Determeining energy losses This CAD tool has been used in the design of receivers such as Javad Positioning Systems (JPS) Legacy, Regency, Odyssey, and Eurocard and in the prediction of their accuracy. It has been shown that experimental and predicted data agree well. ? 2000 John Wiley & Sons, Inc.  相似文献   

Pure P- and S-wave equations in transversely isotropic media     

Alexey Stovas  Tariq Alkhalifah  Umair bin Waheed 《Geophysical Prospecting》2020,68(9):2762-2769

Pure-mode wave propagation is important for applications ranging from imaging to avoiding parameter tradeoff in waveform inversion. Although seismic anisotropy is an elastic phenomenon, pseudo-acoustic approximations are routinely used to avoid the high computational cost and difficulty in decoupling wave modes to obtain interpretable seismic images. However, such approximations may result in inaccuracies in characterizing anisotropic wave propagation. We propose new pure-mode equations for P- and S-waves resulting in an artefact-free solution in transversely isotropic medium with a vertical symmetry axis. Our approximations are more accurate than other known approximations as they are not based on weak anisotropy assumptions. Therefore, the S-wave approximation can reproduce the group velocity triplications in strongly anisotropic media. The proposed approximations can be used for accurate modelling and imaging of pure P- and S-waves in transversely isotropic media.  相似文献   

Effect of anelastic patchy saturated sand layers on the reflection and transmission responses of a periodically layered medium          下载免费PDF全文

Bastien Dupuy  Alexey Stovas 《Geophysical Prospecting》2016,64(2):299-319

Based on analytic relations, we compute the reflection and transmission responses of a periodically layered medium with a stack of elastic shales and partially saturated sands. The sand layers are considered anelastic (using patchy saturation theory) or elastic (with effective velocity). Using the patchy saturation theory, we introduce a velocity dispersion due to mesoscale attenuation in the sand layer. This intrinsic anelasticity is creating frequency dependence, which is added to the one coming from the layering (macroscale). We choose several configurations of the periodically layered medium to enhance more or less the effect of anelasticity. The worst case to see the effect of intrinsic anelasticity is obtained with low dispersion in the sand layer, strong contrast between shales and sands, and a low value of the net‐to‐gross ratio (sand proportion divided by the sand + shale proportion), whereas the best case is constituted by high dispersion, weak contrast, and high net‐to‐gross ratio. We then compare the results to show which dispersion effect is dominating in reflection and transmission responses. In frequency domain, the influence of the intrinsic anelasticity is not negligible compared with the layering effect. Even if the main resonance patterns are the same, the resonance peaks for anelastic cases are shifted towards high frequencies and have a slightly lower amplitude than for elastic cases. These observations are more emphasized when we combine all effects and when the net‐to‐gross ratio increases, whereas the differences between anelastic and elastic results are less affected by the level of intrinsic dispersion and by the contrast between the layers. In the time domain, the amplitude of the responses is significantly lower when we consider intrinsic anelastic layers. Even if the phase response has the same features for elastic and anelastic cases, the anelastic model responses are clearly more attenuated than the elastic ones. We conclude that the frequency dependence due to the layering is not always dominating the responses. The frequency dependence coming from intrinsic visco‐elastic phenomena affects the amplitude of the responses in the frequency and time domains. Considering intrinsic attenuation and velocity dispersion of some layers should be analyzed while looking at seismic and log data in thin layered reservoirs.  相似文献   

Scanning anisotropy parameters in horizontal transversely isotropic media          下载免费PDF全文

Nabil Masmoudi  Alexey Stovas  Tariq Alkhalifah 《Geophysical Prospecting》2017,65(4):981-991

The horizontal transversely isotropic model, with arbitrary symmetry axis orientation, is the simplest effective representative that explains the azimuthal behaviour of seismic data. Estimating the anisotropy parameters of this model is important in reservoir characterisation, specifically in terms of fracture delineation. We propose a travel‐time‐based approach to estimate the anellipticity parameter η and the symmetry axis azimuth ? of a horizontal transversely isotropic medium, given an inhomogeneous elliptic background model (which might be obtained from velocity analysis and well velocities). This is accomplished through a Taylor's series expansion of the travel‐time solution (of the eikonal equation) as a function of parameter η and azimuth angle ?. The accuracy of the travel time expansion is enhanced by the use of Shanks transform. This results in an accurate approximation of the solution of the non‐linear eikonal equation and provides a mechanism to scan simultaneously for the best fitting effective parameters η and ?, without the need for repetitive modelling of travel times. The analysis of the travel time sensitivity to parameters η and ? reveals that travel times are more sensitive to η than to the symmetry axis azimuth ?. Thus, η is better constrained from travel times than the azimuth. Moreover, the two‐parameter scan in the homogeneous case shows that errors in the background model affect the estimation of η and ? differently. While a gradual increase in errors in the background model leads to increasing errors in η, inaccuracies in ?, on the other hand, depend on the background model errors. We also propose a layer‐stripping method valid for a stack of arbitrary oriented symmetry axis horizontal transversely isotropic layers to convert the effective parameters to the interval layer values.  相似文献   

Weak‐anisotropy approximation for P‐wave reflection coefficient at the boundary between two tilted transversely isotropic media          下载免费PDF全文

Yuriy Ivanov  Alexey Stovas 《Geophysical Prospecting》2017,65(2):485-502

Existing and commonly used in industry nowadays, closed‐form approximations for a P‐wave reflection coefficient in transversely isotropic media are restricted to cases of a vertical and a horizontal transverse isotropy. However, field observations confirm the widespread presence of rock beds and fracture sets tilted with respect to a reflection boundary. These situations can be described by means of the transverse isotropy with an arbitrary orientation of the symmetry axis, known as tilted transversely isotropic media. In order to study the influence of the anisotropy parameters and the orientation of the symmetry axis on P‐wave reflection amplitudes, a linearised 3D P‐wave reflection coefficient at a planar weak‐contrast interface separating two weakly anisotropic tilted tranversely isotropic half‐spaces is derived. The approximation is a function of the incidence phase angle, the anisotropy parameters, and symmetry axes tilt and azimuth angles in both media above and below the interface. The expression takes the form of the well‐known amplitude‐versus‐offset “Shuey‐type” equation and confirms that the influence of the tilt and the azimuth of the symmetry axis on the P‐wave reflection coefficient even for a weakly anisotropic medium is strong and cannot be neglected. There are no assumptions made on the symmetry‐axis orientation angles in both half‐spaces above and below the interface. The proposed approximation can be used for inversion for the model parameters, including the orientation of the symmetry axes. Obtained amplitude‐versus‐offset attributes converge to well‐known approximations for vertical and horizontal transverse isotropic media derived by Rüger in corresponding limits. Comparison with numerical solution demonstrates good accuracy.  相似文献   

Biosorption of Re(VII) from Batch Solutions and Industrial Effluents by Cyanobacteria Spirulina platensis          下载免费PDF全文

Inga Zinicovscaia  Alexey Safonov  Irina Troshkina  Ludmila Demina  Konstantin German 《洁净——土壤、空气、水》2018,46(7)

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Estimate of the Upper Limit on Hot Plasma Differential Emission Measure (DEM) in Non-Flaring Active Regions and Nanoflare Frequency Based on the Mg <Emphasis Type="SmallCaps">xii</Emphasis> Spectroheliograph Data from CORONAS-F/SPIRIT     

Anton Reva  Artem Ulyanov  Alexey Kirichenko  Sergey Bogachev  Sergey Kuzin 《Solar physics》2018,293(10):140

Nanoflare-heating theory predicts steady hot-plasma emission in non-flaring active regions. It is hard to find this emission with conventional non-monochromatic imagers (such as the Atmospheric Imaging Assembly or the X-Ray Telescope), because their images contain a cool-temperature background. In this work, we search for hot plasma in non-flaring active regions using the Mg?xii spectroheliograph onboard the Complex Orbital Observations Near-Earth of Activity on the Sun (CORONAS)-F/SPectroheliographIc X-ray Imaging Telescope (SPIRIT). This instrument acquired monochromatic images of the solar corona in the Mg?xii 8.42 Å line, which emits only at temperatures higher than 4 MK. The Mg?xii images only contain the signal from hot plasma, without any low-temperature background. We studied the hot plasma in active regions using SPIRIT data from 18?–?28 February 2002. During this period, the Mg?xii spectroheliograph worked with a 105-second cadence almost without data gaps. Hot plasma was observed only in the flaring active regions. We did not observe any hot plasma in non-flaring active regions. The hot-plasma column emission measure in the non-flaring active region is not expected to exceed \(3 \times10^{24}\) cm^?5. The hot differential emission measure is lower than 0.01% of the DEM of the main temperature component. The absence of Mg?xii emission in the non-flaring active regions can be explained by weak and frequent nanoflares (with a delay of less than 500 seconds) or by very short and intense nanoflares that lead to non-equilibrium ionization.  相似文献   

Effect of a Shift in Diurnal Geomagnetic Variation on the Activity and Sensitivity of Digestive Glycosidases in Roach Underyearlings to Heavy Metals     

Golovanova  I. L.  Filippov  A. A.  Chebotareva  Yu. V.  Urvantseva  G. A.  Krylov  V. V. 《Izvestiya Atmospheric and Oceanic Physics》2019,55(11):1623-1628

Izvestiya, Atmospheric and Oceanic Physics - The effect of temporal shifts in diurnal geomagnetic variation with 6- and 12-h intervals relative to the day–night cycle on the activity of...  相似文献   

Sources of granitoids in the Tuva-Mongolian microcontinent and surrounding structures: Evidence from Pb, Nd, and O isotopic systematics     

G. V. Ovchinnikova  D. P. Krylov  I. K. Kozakov  V. P. Kovach  N. A. Sergeeva 《Petrology》2009,17(6):570-578

Newly obtained data on Pb isotopic ratios in feldspars from Early Proterozoic granitoids of the Sangilen block of the Tuva-Mongolian microcontinent and Caledonian structures surrounding it, considered together with earlier data on the O and Nd isotopic systems, indicate that ancient (approximately 2 Ga) crustal material mixed in the sources of granites of the Tuva-Mongolian microcontinent with younger juvenile material. Positive ɛ_Nd values of granitoids from the Bashkimugor and Chgargalant massifs are accounted for by processes of crustal contamination during the interaction of the melt with crustal material. Similar Nd isotopic characteristics of granitoids in the Khoromnug pluton were caused by the melting of the Late Riphean crust. In granitoids of the massifs in the Kaakhem and Eastern Tannuola zones of the surrounding Caledonian structures, the involvement of juvenile material from oceanic crust increases away from the Sangilen block. Granites in the junction zone between the Tuva-Mongolian microcontinent and surrounding structures display evidence of the presence (up to 10–20%) of an ancient crustal component, and the melting history of granitoids in the Eastern Tannuola zone is dominated by an Early Paleozoic juvenile component in combination with material similar to the Vendian ophiolites of the Agardag-Erzin zone. An increase in the δ¹⁸O value, the ²⁰⁶Pb/²⁰⁴Pb ratio, and the T_Nd(DM) values within a single complex (from older to younger granitoid phases) is explained by the systematic involvement of crustal material in the melting processes.  相似文献